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2015-11-28 19:48:39

SQL Query syntax


1.       Create database

CREATE DATABASE DatabaseName;


2.       drop database

DROP DATABASE DatabaseName;

3.       select database

USE DatabaseName;


4.       create table

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


5.       Drop table

DROP TABLE table_name;

6.       Inset to table

INSERT INTO TABLE_NAME (column1, column2, column3,...columnN)]  
VALUES (value1, value2, value3,...valueN);

7.       select table

SELECT column1, column2, columnN FROM table_name;

8.       WHERE clause

        The SQL WHERE clause is used to specify a condition while fetching the data from single table or joining with multiple tables. If the given condition is satisfied then only it returns specific value from the table. You would use WHERE clause to filter the records and fetching only necessary records.

SELECT column1, column2, columnN 
FROM table_name
WHERE [condition]

9.       AND OR Clause

SELECT column1, column2, columnN 
FROM table_name
WHERE [condition1] AND [condition2]...AND [conditionN];

10.   Update

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


11.   Delete

DELETE FROM table_name
WHERE [condition];


12.   LIKE clause

The percent sign represents zero, one, or multiple characters. The underscore represents a single number or character. The symbols can be used in combinations.

SELECT FROM table_name
WHERE column LIKE 'XXXX%'
 
or 
 
SELECT FROM table_name
WHERE column LIKE '%XXXX%'
 
or
 
SELECT FROM table_name
WHERE column LIKE 'XXXX_'
 
or
 
SELECT FROM table_name
WHERE column LIKE '_XXXX'
 
or
 
SELECT FROM table_name
WHERE column LIKE '_XXXX_'


13.   Top clause

SELECT TOP number|percent column_name(s)
FROM table_name
WHERE [condition]


14.   Oder by

SELECT column-list 
FROM table_name 
[WHERE condition] 
[ORDER BY column1, column2, .. columnN] [ASC | DESC];


15.   Group by

SELECT column1, column2
FROM table_name
WHERE [ conditions ]
GROUP BY column1, column2
ORDER BY column1, column2


16.   DISTINCT ( 唯一)

SELECT DISTINCT column1, column2,.....columnN 
FROM table_name
WHERE [condition]


17.   Inner join

SELECT table1.column1, table2.column2...
FROM table1
INNER JOIN table2
ON table1.common_field = table2.common_field;


18.   Alter

ALTER TABLE table_name ADD column_name datatype;
ALTER TABLE table_name DROP COLUMN column_name;
ALTER TABLE table_name MODIFY COLUMN column_name datatype;
ALTER TABLE table_name MODIFY column_name datatype NOT NULL;
ALTER TABLE table_name ADD CONSTRAINT MyUniqueConstraint UNIQUE(column1, column2...);
ALTER TABLE table_name ADD CONSTRAINT MyUniqueConstraint CHECK (CONDITION);
ALTER TABLE table_name ADD CONSTRAINT MyPrimaryKey PRIMARY KEY (column1, column2...);
ALTER TABLE table_name DROP CONSTRAINT MyUniqueConstraint;
ALTER TABLE table_name DROP INDEX MyUniqueConstraint;
ALTER TABLE table_name DROP CONSTRAINT MyPrimaryKey;


19.  




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