MySql get full name from last first mid name

Using CONCAT_WS to extract full name from first , middle and last name. 

It also handles the case that the mid_name can be empty or null or even have multiple spaces!

SELECT id, email,
    CASE WHEN mid_name IS NULL OR TRIM(mid_name) ='' THEN
        CONCAT_WS( " ", first_name, last_name )
    ELSE
        CONCAT_WS( " ", first_name, mid_name, last_name )
    END AS full_name
FROM USER;

mysql hibernate unicode support - character set, collate

I just did following configurations to achieve Unicode support in my Java+Hibernate+MySQL project.

Configuring MySQL to support Unicode - set Character Set and Collate as :

CREATE TABLE YOUR_DB_NAME
 CHARACTER SET "UTF8"
 COLLATE "utf8_general_ci";

NOTE : You Need to do "ALTER TABLE" instead of "CREATE TABLE", 
      if you are going to modify existing DB.

Hibernate JDBC connection string :

jdbc.url=jdbc:mysql://localhost:3306/YOUR_DB_NAME?useUnicode=true&characterEncoding=UTF-8

Hibernate Configuration:

<hibernate-configuration>
<session-factory>
    ...
    <property name="hibernate.connection.charSet">UTF-8</property>
    <property name="hibernate.connection.characterEncoding">UTF-8</property>
    <property name="hibernate.connection.useUnicode">true</property>
    ...
</session-factory>
</hibernate-configuration>

What's the difference between a primary key and a unique key?

Both primary key and unique enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where unique creates a non-clustered index by default. Another major difference is that, primary key does not allow NULLs, but unique key allows one NULL only.

What is de-normalization and when would you go for it?

As the name indicates, de-normalization is the reverse process of normalization. It is the controlled introduction of redundancy in to the database design. It helps improve the query performance as the number of joins could be reduced.

What are clustered index and non clustered index

With a clustered index the rows are stored physically on the disk in the same order as the index. There can therefore be only one clustered index.

With a non clustered index there is a second list that has pointers to the physical rows. You can have many non clustered indexes, although each new index will increase the time it takes to write new records.

It is generally faster to read from a clustered index if you want to get back all the columns. You do not have to go first to the index and then to the table.

Writing to a table with a clustered index can be slower, if there is a need to rearrange the data.

In other words,
A clustered index means you are telling the database to store close values actually close to one another on the disk. This has the benefit of rapid scan / retrieval of records falling into some range of clustered index values.


From Wikipedia :
A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of slower writes and increased storage space

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)

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)

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 )

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 ] }