SQL Cheatsheet

Author: Doe Hoon LEE

English

A_

(1) AVG()

• a function that returns average value of a column (according to the condition given)

SELECT AVG([ColumnName1])
FROM [TableName]
-- WHERE Condition;

B_

(1) BETWEEN

• returns rows where the records falls between A and B

SELECT [ColumnName]
FROM [TableName]
WHERE ColumnName BETWEEN Value1 AND Value2;

C_

(1) COUNT()

• a function that returns number of rows (according to the condition given)

SELECT COUNT (DISTINCT [ColumnName]) 
FROM [TableName]
-- WHERE Condition;

D_

(1) DELETE

• deletes a row according to the condition given

DELETE FROM [TableName]
WHERE condition;

• this will delete all the rows unless you specify the condition

(2) DISTINCT

• selectively returns distinct/unique values only

SELECT DISTINCT [ColumnName1], [ColumnName2], ...
FROM [TableName];

(3) DIFFERENCE

SELECT COUNT([ColumnName1]) - COUNT([ColumnName2])
FROM [TableName];

I_

(1) INSERT INTO

• insert new record in a table

INSERT INTO [TableName] ([ColumnName1], [ColumnName2], [ColumnName3], ...)
VALUES (Value1, Value2, Value3, ...);

L_

(1) LIKE

• is used with WHERE specifying condition
• selects records with given pattern

SELECT [ColumnName1], [ColumnName2], ...
FROM [TableName]
WHERE [ColumnName] LIKE pattern;

LIKE + pattern	Looking For
LIKE ‘a%’	value that starts with “a”
LIKE ‘%e’	value that ends with “e”
LIKE ‘a%e’	value that starts with “a” and ends with “e”
LIKE ‘_t’	value where the 2nd letter is “t”
LIKE ‘t___’	value that starts with “t” and the length is 4
LIKE ‘a%’	value that starts with “a”

M_

(1) MIN() & MAX()

• a function that returns the smallest/largets value from the column

SELECT MIN([ColumnName1])
FROM [TableName];

SELECT MAX([ColumnName1])
FROM [TableName];

O_

(1) Operators - AND, OR, NOT, IN

SELECT [ColumnName1], [ColumnName2], ...
FROM [TableName]
WHERE condition1 AND | OR condition2;

SELECT [ColumnName1], [ColumnName2], ...
FROM [TableName]
WHERE NOT condition1;

• IN allows multiple conditions in WHERE

SELECT [ColumnName]
FROM [TableName]
WHERE ColumnName IN (Value1, Value2, ...);

(2) ORDER BY ASC (DESC)

• it sorts records in ascedning/descending order

SELECT [CoumnName]
FROM [TableName]
ORDER BY [ColumnName] ASC | DESC;

S_

(1) SELECT

• is used for extracting data you want
• make sure to specify WHICH data you would like to get and WHERE you want it from

SELECT [ColumnName1], [ColumnName2], ...
FROM [TableName];

(2) SUM()

• a function that returns the total sum of values of a column

SELECT COUNT([ColumnName1)
FROM [TableName];

T_

(1) TOP

• SELECTS TOP number of records

SELECT TOP 3 * FROM [ColumnName]
WHERE condition;

-- OR

SELECT * FROM [ColumnName]
WHERE condition
LIMIT 3;

U_

(1) UPDATE

• updates records in a table

UPDATE [TableName]
SET ColumnName1=Value1, ColumnName2=Value2, ...
WHERE Condition;

NOTE!! if condition is not set, all the records will be updated!

W_

(1) WHERE

• is used for conditionally selecting data

SELECT * FROM [ColumnName1]
WHERE Name='Seoul';

• select data where Name = ‘Seoul’

SELECT * FROM [ColumnName1]
WHERE Name<>'Seoul';

• select data where Name is NOT ‘Seoul’

한국어

SQL 치트시트