SQL是关系型数据库的查询语言，因为不常用所以经常忘记。这里记录一些简单的命令，以备查询。

注意SQL语句需要以;号结尾.

1. SQL SELECT Statement:

SELECT column1, column2....columnN 
FROM table_name;

1. SQL DISTINCT Clause:

SELECT DISTINCT column1, column2....columnN
FROM table_name;

1. SQL WHERE Clause:

SELECT column1, column2....columnN
FROM table_name
WHERE CONDITION;

1. SQL AND/OR Clause:

SELECT column1, column2....columnN
FROM table_name
WHERE CONDITION-1 {AND|OR} CONDITION-2;

1. SQL IN Clause:

SELECT column1, column2....columnN
FROM table_name
WHERE column_name IN (val-1, val-2,...val-N);

1. SQL BETWEEN Clause:

SELECT column1, column2....columnN
FROM table_name
WHERE column_name BETWEEN val-1 AND val-2;

1. SQL LIKE Clause:

SELECT column1, column2....columnN
FROM table_name
WHERE column_name LIKE { PATTERN };

1. SQL ORDER BY Clause:

SELECT column1, column2....columnN
FROM table_name
WHERE CONDITIONORDER BY column_name {ASC|DESC};

1. SQL GROUP BY Clause:

SELECT SUM(column_name)
FROM table_name
WHERE CONDITIONGROUP BY column_name;

1. SQL COUNT Clause:

SELECT COUNT(column_name)
FROM table_name
WHERE CONDITION;

1. SQL HAVING Clause:

SELECT SUM(column_name)
FROM table_name
WHERE CONDITIONGROUP BY column_name
HAVING (arithematic function condition);

1. SQL CREATE TABLE Statement:

CREATE TABLE table_name(
column1 datatype,
column2 datatype,
column3 datatype,
.....
columnN datatype,
PRIMARY KEY( one or more columns )
);

1. SQL DROP TABLE Statement:

DROP TABLE table_name;

1. SQL CREATE INDEX Statement :

CREATE UNIQUE INDEX index_name
ON table_name ( column1, column2,...columnN);

1. SQL DROP INDEX Statement :

ALTER TABLE table_name DROP INDEX index_name;

1. SQL DESC Statement :

DESC table_name;

1. SQL TRUNCATE TABLE Statement:

TRUNCATE TABLE table_name;

1. SQL ALTER TABLE Statement:

ALTER TABLE table_name {ADD|DROP|MODIFY} column_name {data_ype};

1. SQL ALTER TABLE Statement (Rename) :

ALTER TABLE table_name RENAME TO new_table_name;

1. SQL INSERT INTO Statement:

INSERT INTO table_name( column1, column2....columnN)
VALUES ( value1, value2....valueN);

1. SQL UPDATE Statement:

UPDATE table_name
SET column1 = value1, column2 = value2....columnN=valueN
[ WHERE CONDITION ];

1. SQL DELETE Statement:

DELETE FROM table_name
WHERE {CONDITION};

1. SQL CREATE DATABASE Statement:

CREATE DATABASE database_name;

1. SQL DROP DATABASE Statement:

DROP DATABASE database_name;

1. SQL USE Statement:

USE database_name;

1. SQL COMMIT Statement:

COMMIT;

1. SQL ROLLBACK Statement:

ROLLBACK; 

这些内容来自：http://www.tutorialspoint.com/sql/sql-syntax.htm 这是一个学习SQL的好站点。