long startTime = System.currentTimeMillis();
doReallyLongThing(); // call your method here
long endTime = System.currentTimeMillis();
// calculate the difference - that the method just took to executeSystem.out.println("That took " + (endTime - startTime) + " milliseconds");
java calculate method run time
SQL basics- complete reference guide - part8 SQL System Commands
Part8: SQL System Commands Reference guide
TOPIC | TEXT | SYNTAX | Example |
---|---|---|---|
ARRAY_GET | Returns one element of an array. | ARRAY_GET(arrayExpression, indexExpression) | |
ARRAY_LENGTH | Returns the length of an array. | ARRAY_GET(arrayExpression) | |
AUTOCOMMIT | Returns true if auto commit is switched on for this session. | AUTOCOMMIT() | |
CANCEL_SESSION | Cancels the currently executing statement of another session. | CANCEL_SESSION(sessionInt) | |
CASEWHEN Function | Returns 'a' if the boolean expression is true, otherwise 'b'. | CASEWHEN(boolean, aValue, bValue) | |
CAST | Converts a value to another data type. | CAST(value AS dataType) | |
COALESCE | Returns the first value that is not null. | COALESCE(aValue, bValue [,...]) | |
CONVERT | Converts a value to another data type. | CONVERT(value, dataType) | |
CURRVAL | Returns the current (last) value of the sequence, independent of the session. | CURRVAL( [ schemaName, ] sequenceString ) | |
CSVREAD | Returns the result set of reading the CSV (comma separated values) file. | CSVREAD(fileNameString [, columnsString [, csvOptions ] ] ) | |
CSVWRITE | Writes a CSV (comma separated values). | CSVWRITE ( fileNameString, queryString [, csvOptions [, lineSepString] ] ) | |
DATABASE | Returns the name of the database. | DATABASE() | |
DATABASE_PATH | Returns the directory of the database files and the database name, if it is file based. | DATABASE_PATH() | |
FILE_READ | Returns the contents of a file. | FILE_READ(fileNameString [,encodingString]) | |
GREATEST | Returns the largest value that is not NULL, or NULL if all values are NULL. | GREATEST(aValue, bValue [,...]) | |
IDENTITY | Returns the last inserted identity value for this session. | IDENTITY() | |
IFNULL | Returns the value of 'a' if it is not null, otherwise 'b'. | IFNULL(aValue, bValue) | |
LEAST | Returns the smallest value that is not NULL, or NULL if all values are NULL. | LEAST(aValue, bValue [,...]) | |
LOCK_MODE | Returns the current lock mode. | LOCK_MODE() | |
LOCK_TIMEOUT | Returns the lock timeout of the current session (in milliseconds). | LOCK_TIMEOUT() | |
LINK_SCHEMA | Creates table links for all tables in a schema. | LINK_SCHEMA(targetSchemaString, driverString, urlString, userString, passwordString, sourceSchemaString) | |
MEMORY_FREE | Returns the free memory in KB (where 1024 bytes is a KB). | MEMORY_FREE() | |
MEMORY_USED | Returns the used memory in KB (where 1024 bytes is a KB). | MEMORY_USED() | |
NEXTVAL | Returns the next value of the sequence. | NEXTVAL ( [ schemaName, ] sequenceString ) | |
NULLIF | Returns NULL if 'a' is equals to 'b', otherwise 'a'. | NULLIF(aValue, bValue) | |
READONLY | Returns true if the database is read-only. | READONLY() | |
ROWNUM | Returns the number of the current row. | ROWNUM() | |
SCHEMA | Returns the name of the default schema for this session. | SCHEMA() | |
SCOPE_IDENTITY | Returns the last inserted identity value for this session for the current scope. | SCOPE_IDENTITY() | |
SESSION_ID | Returns the unique session id number for the current database connection. | SESSION_ID() | |
SET | Updates a variable with the given value. | SET(@variableName, value) | |
TABLE | Returns the result set. | { TABLE | TABLE_DISTINCT } ( { name dataType = expression } [,...] ) | |
TRANSACTION_ID | Returns the current transaction id for this session. | TRANSACTION_ID() | |
USER | Returns the name of the current user of this session. | { USER | CURRENT_USER } () | Select User(); |
SQL basics- complete reference guide - part7 - Date Time Functions
Part7: SQL Date Time Functions Reference
TOPIC | TEXT | SYNTAX | Example |
---|---|---|---|
CURRENT_DATE | Returns the current date. | { CURRENT_DATE [ () ] | CURDATE() | SYSDATE | TODAY } | |
CURRENT_TIME | Returns the current time. | { CURRENT_TIME [ () ] | CURTIME() } | |
CURRENT_TIMESTAMP | Returns the current timestamp. | { CURRENT_TIMESTAMP [ ( [ int ] ) ] | NOW( [ int ] ) } | |
DATEADD | Adds units to a timestamp. | DATEADD(unitString, addInt, timestamp) | |
DATEDIFF | Returns the the number of crossed unit boundaries between two timestamps. | { DATEDIFF | TIMESTAMPDIFF } (unitString, aTimestamp, bTimestamp) | |
DAYNAME | Returns the name of the day (in English). | DAYNAME(date) | |
DAY_OF_MONTH | Returns the day of the month (1-31). | DAY_OF_MONTH(date) | |
DAY_OF_WEEK | Returns the day of the week (1 means Sunday). | DAY_OF_WEEK(date) | |
DAY_OF_YEAR | Returns the day of the year (1-366). | DAY_OF_YEAR(date) | |
EXTRACT | Returns a specific value from a timestamps. | EXTRACT ( { YEAR | YY | MONTH | MM | DAY | DD | DAY_OF_YEAR | DOY | HOUR | HH | MINUTE | MI | SECOND | SS | MILLISECOND | MS } FROM timestamp ) | |
FORMATDATETIME | Formats a date, time or timestamp as a string. | FORMATDATETIME ( timestamp, formatString [ , localeString [ , timeZoneString ] ] ) | |
HOUR | Returns the hour (0-23) from a timestamp. | HOUR(timestamp) | |
MINUTE | Returns the minute (0-59) from a timestamp. | MINUTE(timestamp) | |
MONTH | Returns the month (1-12) from a timestamp. | MONTH(timestamp) | |
MONTHNAME | Returns the name of the month (in English). | MONTHNAME(date) | |
PARSEDATETIME | Parses a string and returns a timestamp. | PARSEDATETIME(string, formatString [, localeString [, timeZoneString]]) | |
QUARTER | Returns the quarter (1-4) from a timestamp. | QUARTER(timestamp) | |
SECOND | Returns the second (0-59) from a timestamp. | SECOND(timestamp) | |
WEEK | Returns the week (1-53) from a timestamp. | WEEK(timestamp) | |
YEAR | Returns the year from a timestamp. | YEAR(timestamp) |
Java Capture/save image from swing Component eg : JFrame JPanel ..
Capture image from any swing Component and save to file.
Capture :
Capture :
BufferedImage image = new BufferedImage(component.getWidth(),
component.getHeight(), BufferedImage.TYPE_INT_RGB);
// paints into image's Graphics
component.paint(image.getGraphics());
Save Image :SQL basics- complete reference guide - part6 - String functions
Part6: SQL String Functions Complete Reference
TOPIC | TEXT | SYNTAX | Example |
---|---|---|---|
ASCII | Returns the ASCII value of the first character in the string. | ASCII(string) | |
BIT_LENGTH | Returns the number of bits in a string. | BIT_LENGTH(string) | |
LENGTH | Returns the number of characters in a string. | { LENGTH | CHAR_LENGTH | CHARACTER_LENGTH } ( string ) | |
OCTET_LENGTH | Returns the number of bytes in a string. | OCTET_LENGTH(string) | |
CHAR | Returns the character that represents the ASCII value. | { CHAR | CHR } ( int ) | |
CONCAT | Combines strings. | CONCAT(string, string [,...]) | |
DIFFERENCE | Returns the difference between the sounds of two strings. | DIFFERENCE(string, string) | |
HEXTORAW | Converts a hex representation of a string to a string. | HEXTORAW(string) | |
RAWTOHEX | Converts a string to the hex representation. | RAWTOHEX(string) | |
INSTR | Returns the location of a search string in a string. | INSTR(string, searchString, [, startInt]) | |
INSERT Function | Inserts a additional string into the original string at a specified start position. | INSERT(originalString, startInt, lengthInt, addString) | |
LOWER | Converts a string to lowercase. | { LOWER | LCASE } ( string ) | |
UPPER | Converts a string to uppercase. | { UPPER | UCASE } ( string ) | |
LEFT | Returns the leftmost number of characters. | LEFT(string, int) | |
RIGHT | Returns the rightmost number of characters. | RIGHT(string, int) | |
LOCATE | Returns the location of a search string in a string. | LOCATE(searchString, string [, startInt]) | |
POSITION | Returns the location of a search string in a string. | POSITION(searchString, string) | |
LPAD | Left pad the string to the specified length. | LPAD(string, int[, paddingString]) | |
RPAD | Right pad the string to the specified length. | RPAD(string, int[, paddingString]) | |
LTRIM | Removes all leading spaces from a string. | LTRIM(string) | |
RTRIM | Removes all trailing spaces from a string. | RTRIM(string) | |
TRIM | Removes all leading spaces, trailing spaces, or spaces at both ends, from a string. | TRIM ( [ { LEADING | TRAILING | BOTH } [ string ] FROM ] string ) | |
REGEXP_REPLACE | Replaces each substring that matches a regular expression. | REGEXP_REPLACE(inputString, regexString, replacementString) | |
REPEAT | Returns a string repeated some number of times. | REPEAT(string, int) | |
REPLACE | Replaces all occurrences of a search string in a text with another string. | REPLACE(string, searchString [, replacementString]) | |
SOUNDEX | Returns a four character code representing the sound of a string. | SOUNDEX(string) | |
SPACE | Returns a string consisting of a number of spaces. | SPACE(int) | |
STRINGDECODE | Converts a encoded string using the Java string literal encoding format. | STRINGDECODE(string) | |
STRINGENCODE | Encodes special characters in a string using the Java string literal encoding format. | STRINGENCODE(string) | |
STRINGTOUTF8 | Encodes a string to a byte array using the UTF8 encoding format. | STRINGTOUTF8(string) | |
SUBSTRING | Returns a substring of a string starting at a position. | { SUBSTRING | SUBSTR } ( string, startInt [, lengthInt ] ) | |
UTF8TOSTRING | Decodes a byte array in the UTF8 format to a string. | UTF8TOSTRING(bytes) | |
XMLATTR | Creates an XML attribute element of the form "name=value". | XMLATTR(nameString, valueString) | |
XMLNODE | Create an XML node element. | XMLNODE(elementString [, attributesString [, contentString]]) | |
XMLCOMMENT | Creates an XML comment. | XMLCOMMENT(commentString) | |
XMLCDATA | Creates an XML CDATA element. | XMLCDATA(valueString) | |
XMLSTARTDOC | The string " | XMLSTARTDOC() | |
XMLTEXT | Creates an XML text element. | XMLTEXT(valueString) |
java pad string left right - String.format() method
String.format() can be used to left/right pad a given string.
public static String padRight(String s, int n) {
return String.format("%1$-" + n + "s", s); }
public static String padLeft(String s, int n) {
return String.format("%1$#" + n + "s", s); }
...
public static void main(String args[]) throws Exception {
System.out.println(padRight("Howto", 20) + "*");
System.out.println(padLeft("Howto", 25) + "*");
}
Top Java Interview Question : reverse a string using recursion
Best Answer using Recursion :
Less Best Answer :
public String reverse(String str) {
if ((null == str) || (str.length() <= 1)) {
return str;
}
return reverse(str.substring(1)) + str.charAt(0);
}
Less Best Answer :
public class JdkReverser implements Reverser {
public String reverse(String str) {
if ((null == str) || (str.length() <= 1)) {
return str;
}
return new StringBuffer(str).reverse().toString();
}
}
SQL basics- complete reference guide - part5 - Mathematical Functions
Part5: Mathematical Functions in SQL- Complete Reference
Function | Description | SYNTAX | Example |
---|---|---|---|
ABS | ABS ( { int | long | decimal | double } ) | ||
ACOS | ACOS(double) | ||
ASIN | ASIN(double) | ||
ATAN | ATAN(double) | ||
COS | COS(double) | ||
COT | COT(double) | ||
SIN | SIN(double) | ||
TAN | TAN(double) | ||
ATAN2 | ATAN2(double, double) | ||
BITAND | The bitwise AND operation. | BITAND(long, long) | |
BITOR | The bitwise OR operation. | BITOR(long, long) | |
BITXOR | The bitwise XOR operation. | BITXOR(long, long) | |
MOD | The modulo operation. | MOD(long, long) | |
CEILING | CEILING(double) | ||
DEGREES | DEGREES(double) | ||
EXP | EXP(double) | ||
FLOOR | FLOOR(double) | ||
LOG | LOG(double) | ||
LOG10 | LOG10(double) | ||
RADIANS | RADIANS(double) | ||
SQRT | SQRT(double) | ||
PI | PI() | ||
POWER | POWER(double, double) | ||
RAND | Calling the function without parameter returns the next a pseudo random number. | RAND( [ int ] ) | |
RANDOM_UUID | Returns a new UUID with 122 pseudo random bits. | RANDOM_UUID() | |
ROUND | Rounds to a number of digits. | ROUND(double, digitsInt) | |
ROUNDMAGIC | This function rounds numbers in a good way, but it is slow. | ROUNDMAGIC(double) | |
SECURE_RAND | Generates a number of cryptographically secure random numbers. | SECURE_RAND(int) | |
SIGN | Returns -1 if the value is smaller 0, 0 if zero, and otherwise 1. | SIGN ( { int | long | decimal | double } ) | |
ENCRYPT | Encrypts data using a key. | ENCRYPT(algorithmString, keyBytes, dataBytes) | |
DECRYPT | Decrypts data using a key. | DECRYPT(algorithmString, keyBytes, dataBytes) | |
HASH | Calculate the hash value using an algorithm, and repeat this process for a number of iterations. | HASH(algorithmString, dataBytes, iterationInt) | |
TRUNCATE | Truncates to a number of digits (to the next value closer to 0). | TRUNCATE(double, digitsInt) | |
COMPRESS | Compresses the data using the specified compression algorithm. | COMPRESS(dataBytes [, algorithmString]) | |
EXPAND | Expands data that was compressed using the COMPRESS function. | EXPAND(bytes) | |
ZERO | Returns the value 0. | ZERO() |
SQL basics- complete reference guide - part4 - Aggregate Functions in SQL
Part4: Aggregate Functions in SQL- complete reference sheet
Command/Function | Description | SYNTAX | Example |
---|---|---|---|
AVG | The average (mean) value. | AVG ( [ DISTINCT ] { int | long | decimal | double } ) | |
BOOL_AND | Returns true if all expressions are true. | BOOL_AND(boolean) | |
BOOL_OR | Returns true if any expression is true. | BOOL_OR(boolean) | |
COUNT | The count of all row, or of the non-null values. | COUNT( { * | { [ DISTINCT ] expression } } ) | |
GROUP_CONCAT | Concatenates strings with a separator. | GROUP_CONCAT ( [ DISTINCT ] string [ ORDER BY { expression [ ASC | DESC ] } [,...] ] [ SEPARATOR expression ] ) | |
MAX | The highest value. | MAX(value) | |
MIN | The lowest value. | MIN(value) | |
SUM | The sum of all values. | SUM( [ DISTINCT ] { int | long | decimal | double } ) | |
SELECTIVITY | Estimates the selectivity (0-100) of a value. | SELECTIVITY(value) | |
STDDEV_POP | The population standard deviation. | STDDEV_POP( [ DISTINCT ] double ) | |
STDDEV_SAMP | The sample standard deviation. | STDDEV_SAMP( [ DISTINCT ] double ) | |
VAR_POP | The population variance (square of the population standard deviation). | VAR_POP( [ DISTINCT ] double ) | |
VAR_SAMP | The sample variance (square of the sample standard deviation). | VAR_SAMP( [ DISTINCT ] double ) |
Call one constructor from another in Java
Is this possible to call one constructor from another in Java ?
Yes, it is possible:
Yes, it is possible:
public class Foo
{
private int x;
public Foo()
{
this(1);//calling constructor -->> public Foo(int x)
}
public Foo(int x)
{
this.x = x;
}
}
SQL basics- complete reference guide - part3 - Data Types in SQL
Part3: SQL Data Types Reference
TOPIC | TEXT | SYNTAX | Example |
---|---|---|---|
INT Type | Possible values: -2147483648 to 2147483647. | INT | INTEGER | MEDIUMINT | INT4 | SIGNED | |
BOOLEAN Type | Possible values: TRUE and FALSE. | BOOLEAN | BIT | BOOL | |
TINYINT Type | Possible values are: -128 to 127. | TINYINT | |
SMALLINT Type | Possible values: -32768 to 32767. | SMALLINT | INT2 | YEAR | |
BIGINT Type | Possible values: -9223372036854775808 to 9223372036854775807. | BIGINT | INT8 | |
IDENTITY Type | Auto-Increment value. | IDENTITY | |
DECIMAL Type | Data type with fixed precision and scale. | { DECIMAL | NUMBER | DEC | NUMERIC } ( precisionInt [ , scaleInt ] ) | |
DOUBLE Type | Floating point number. | { DOUBLE [ PRECISION ] | FLOAT | FLOAT4 | FLOAT8 } | |
REAL Type | Single precision floating point number. | REAL | |
TIME Type | The format is hh:mm:ss. | TIME | |
DATE Type | The format is yyyy-MM-dd. | DATE | |
TIMESTAMP Type | The format is yyyy-MM-dd hh:mm:ss[. | { TIMESTAMP | DATETIME | SMALLDATETIME } | |
BINARY Type | Represents a byte array. | { BINARY | VARBINARY | LONGVARBINARY | RAW | BYTEA } [ ( precisionInt ) ] | |
OTHER Type | This type allows storing serialized Java objects. | OTHER | |
VARCHAR Type | Unicode String. | { VARCHAR | LONGVARCHAR | VARCHAR2 | NVARCHAR | NVARCHAR2 | VARCHAR_CASESENSITIVE} [ ( precisionInt ) ] | |
VARCHAR_IGNORECASE Type | Same as VARCHAR, but not case sensitive when comparing. | VARCHAR_IGNORECASE [ ( precisionInt ) ] | |
CHAR Type | This type is supported for compatibility with other databases and older applications. | { CHAR | CHARACTER | NCHAR } [ ( precisionInt ) ] | |
BLOB Type | Like BINARY, but intended for very large values such as files or images. | { BLOB | TINYBLOB | MEDIUMBLOB | LONGBLOB | IMAGE | OID } [ ( precisionInt ) ] | |
CLOB Type | CLOB is like VARCHAR, but intended for very large values. | { CLOB | TINYTEXT | TEXT | MEDIUMTEXT | LONGTEXT | NTEXT | NCLOB } [ ( precisionInt ) ] | |
UUID Type | Universally unique identifier. | UUID | |
ARRAY Type | An array of values. | ARRAY |
SQL basics- complete reference guide - part2 - DDL
Part2: DDL -Data Definition Language Reference
Command | Description | SYNTAX | Example |
---|---|---|---|
ALTER INDEX RENAME | Renames an index. | ALTER INDEX indexName RENAME TO newIndexName | |
ALTER SCHEMA RENAME | Renames a schema. | ALTER SCHEMA schema RENAME TO newSchemaName | |
ALTER SEQUENCE | Changes the next value and the increment of a sequence. | ALTER SEQUENCE sequenceName [ RESTART WITH long ] [ INCREMENT BY long ] | |
ALTER TABLE ADD | Adds a new column to a table. | ALTER TABLE tableName ADD name dataType [ DEFAULT expression ] [ [ NOT ] NULL ] [ AUTO_INCREMENT | IDENTITY ] [ BEFORE columnName ] | |
ALTER TABLE ADD CONSTRAINT | Adds a constraint to a table. | ALTER TABLE tableName ADD constraint [ CHECK | NOCHECK ] | |
ALTER TABLE ALTER | Changes the data type of a column, rename a column, change the identity value, or change the selectivity. | ALTER TABLE tableName ALTER COLUMN columnName { { dataType [ DEFAULT expression ] [ [ NOT ] NULL ] [ AUTO_INCREMENT | IDENTITY ] } | { RENAME TO name } | { RESTART WITH long } | { SELECTIVITY int } | { SET DEFAULT expression } | { SET NULL } | { SET NOT NULL } } | |
ALTER TABLE DROP COLUMN | Removes a column from a table. | ALTER TABLE tableName DROP COLUMN columnName | |
ALTER TABLE DROP CONSTRAINT | Removes a constraint or a primary key from a table. | ALTER TABLE tableName DROP { CONSTRAINT [ IF EXISTS ] constraintName | PRIMARY KEY } | |
ALTER TABLE SET | Disables or enables referential integrity checking for a table. | ALTER TABLE tableName SET REFERENTIAL_INTEGRITY { FALSE | TRUE [ CHECK | NOCHECK ] } | |
ALTER TABLE RENAME | Renames a table. | ALTER TABLE tableName RENAME TO newName | |
ALTER USER ADMIN | Switches the admin flag of a user on or off. | ALTER USER userName ADMIN { TRUE | FALSE } | |
ALTER USER RENAME | Renames a user. | ALTER USER userName RENAME TO newUserName | |
ALTER USER SET PASSWORD | Changes the password of a user. | ALTER USER userName SET { PASSWORD string | SALT bytes HASH bytes } | |
ALTER VIEW | Recompiles a view after the underlying tables have been changed or created. | ALTER VIEW viewName RECOMPILE | |
ANALYZE | Updates the selectivity statistics of all tables. | ANALYZE [ SAMPLE_SIZE rowCountInt ] | |
COMMENT | Sets the comment of a database object. | COMMENT ON { { COLUMN [ schemaName. ] tableName.columnName } | { { TABLE | VIEW | CONSTANT | CONSTRAINT | ALIAS | INDEX | ROLE | SCHEMA | SEQUENCE | TRIGGER | USER | DOMAIN } [ schemaName. ] objectName } } IS expression | |
CREATE AGGREGATE | Creates a new user-defined aggregate function. | CREATE AGGREGATE [ IF NOT EXISTS ] newAggregateName FOR className | |
CREATE ALIAS | Creates a new function alias. | CREATE ALIAS [ IF NOT EXISTS ] newFunctionAliasName [ DETERMINISTIC ] { FOR classAndMethodName | AS sourceCodeString } | |
CREATE CONSTANT | Creates a new constant. | CREATE CONSTANT [ IF NOT EXISTS ] newConstantName VALUE expression | |
CREATE DOMAIN | Creates a new data type (domain). | CREATE DOMAIN [ IF NOT EXISTS ] newDomainName AS dataType [ DEFAULT expression ] [ [ NOT ] NULL ] [ SELECTIVITY selectivity ] [ CHECK condition ] | |
CREATE INDEX | Creates a new index. | CREATE { [ UNIQUE ] [ HASH ] INDEX [ IF NOT EXISTS ] newIndexName | PRIMARY KEY [ HASH ] } ON tableName ( indexColumn [,...] ) | |
CREATE LINKED TABLE | Creates a table link to an external table. | CREATE [ [ GLOBAL | LOCAL ] TEMPORARY ] LINKED TABLE [ IF NOT EXISTS ] name ( driverString, urlString, userString, passwordString, [ originalSchemaString, ] originalTableString ) [ EMIT UPDATES | READONLY ] | |
CREATE ROLE | Creates a new role. | CREATE ROLE [ IF NOT EXISTS ] newRoleName | |
CREATE SCHEMA | Creates a new schema. | CREATE SCHEMA [ IF NOT EXISTS ] name [ AUTHORIZATION ownerUserName ] | |
CREATE SEQUENCE | Creates a new sequence. | CREATE SEQUENCE [ IF NOT EXISTS ] newSequenceName [ START WITH long ] [ INCREMENT BY long ] [ CACHE long ] | |
CREATE TABLE | Creates a new table. | CREATE [ CACHED | MEMORY ] [ TEMP | [ GLOBAL | LOCAL ] TEMPORARY ] TABLE [ IF NOT EXISTS ] name { { ( { columnDefinition | constraint } [,...] ) [ AS select ] } | { AS select } } [ ENGINE tableEngineName ] [ TRANSACTIONAL ] [ NOT PERSISTENT ] | |
CREATE TRIGGER | Creates a new trigger. | CREATE TRIGGER [ IF NOT EXISTS ] newTriggerName { BEFORE | AFTER | INSTEAD OF } { INSERT | UPDATE | DELETE | SELECT | ROLLBACK } [,...] ON tableName [ FOR EACH ROW ] [ QUEUE int ] [ NOWAIT ] CALL triggeredClassName | |
CREATE USER | Creates a new user. | CREATE USER [ IF NOT EXISTS ] newUserName { PASSWORD string | SALT bytes HASH bytes } [ ADMIN ] | |
CREATE VIEW | Creates a new view. | CREATE [ OR REPLACE ] [ FORCE ] VIEW [ IF NOT EXISTS ] newViewName [ ( columnName [,...] ) ] AS select | |
DROP AGGREGATE | Drops an existing user-defined aggregate function. | DROP AGGREGATE [ IF EXISTS ] aggregateName | |
DROP ALIAS | Drops an existing function alias. | DROP ALIAS [ IF EXISTS ] existingFunctionAliasName | |
DROP ALL OBJECTS | Drops all existing views, tables, sequences, schemas, function aliases, roles, user-defined aggregate functions, domains, and users (except the current user). | DROP ALL OBJECTS [ DELETE FILES ] | |
DROP CONSTANT | Drops a constant. | DROP CONSTANT [ IF EXISTS ] constantName | |
DROP DOMAIN | Drops a data type (domain). | DROP DOMAIN [ IF EXISTS ] domainName | |
DROP INDEX | Drops an index. | DROP INDEX [ IF EXISTS ] indexName | |
DROP ROLE | Drops a role. | DROP ROLE [ IF EXISTS ] roleName | |
DROP SCHEMA | Drops a schema. | DROP SCHEMA [ IF EXISTS ] schemaName | |
DROP SEQUENCE | Drops a sequence. | DROP SEQUENCE [ IF EXISTS ] sequenceName | |
DROP TABLE | Drops an existing table, or a list of tables. | DROP TABLE [ IF EXISTS ] tableName [,...] [ CASCADE | RESTRICT ] | |
DROP TRIGGER | Drops an existing trigger. | DROP TRIGGER [ IF EXISTS ] triggerName | |
DROP USER | Drops a user. | DROP USER [ IF EXISTS ] userName | |
DROP VIEW | Drops an existing view. | DROP VIEW [ IF EXISTS ] viewName [ RESTRICT | CASCADE ] | |
TRUNCATE TABLE | Removes all rows from a table. | TRUNCATE TABLE tableName |
SQL basics- complete reference guide - part1 - DML
Part1: DML-Data Manipulation Language
Command | Description | SYNTAX | Example |
---|---|---|---|
SELECT | Selects data from a table or multiple tables. | SELECT [ TOP term ] [ DISTINCT | ALL ] selectExpression [,...] FROM tableExpression [,...] [ WHERE expression ] [ GROUP BY expression [,...] ] [ HAVING expression ] [ { UNION [ ALL ] | MINUS | EXCEPT | INTERSECT } select ] [ ORDER BY order [,...] ] [ LIMIT expression [ OFFSET expression ] [ SAMPLE_SIZE rowCountInt ] ] [ FOR UPDATE ] | |
INSERT | Inserts a new row / new rows into a table. | INSERT INTO tableName [ ( columnName [,...] ) ] { VALUES { ( { DEFAULT | expression } [,...] ) } [,...] | [ DIRECT ] [ SORTED ] select } | |
UPDATE | Updates data in a table. | UPDATE tableName [ [ AS ] newTableAlias ] SET { columnName= { DEFAULT | expression } } [,...] [ WHERE expression ] | |
DELETE | Deletes rows form a table. | DELETE FROM tableName [ WHERE expression ] | |
BACKUP | Backs up the database files to a . | BACKUP TO fileNameString | |
CALL | Calculates a simple expression. | CALL expression | |
EXPLAIN | Shows the execution plan for a statement. | EXPLAIN { [ PLAN FOR ] | ANALYZE } { select | insert | update | delete | merge } | |
MERGE | Updates existing rows, and insert rows that don't exist. | MERGE INTO tableName [ ( columnName [,...] ) ] [ KEY ( columnName [,...] ) ] { VALUES { ( { DEFAULT | expression } [,...] ) } [,...] | select } | |
RUNSCRIPT | Runs a SQL script from a file. | RUNSCRIPT FROM fileNameString [ scriptCompression ] [ CIPHER cipher PASSWORD string ] [ CHARSET charsetString ] | |
SCRIPT | Creates a SQL script from the database. | SCRIPT [ SIMPLE ] [ NODATA ] [ NOPASSWORDS ] [ NOSETTINGS ] [ DROP ] [ BLOCKSIZE blockSizeInt ] [ TO fileNameString [ scriptCompression ] [ CIPHER cipher PASSWORD string ] ] [ CHARSET charsetString ] | |
SHOW | Lists the schemas, tables, or the columns of a table. | SHOW { SCHEMAS | TABLES [ FROM schemaName ] | COLUMNS FROM tableName [ FROM schemaName ] } |
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