sql-cheatsheet

Personal cheat sheet for querying relational database in SQL SERVER

Basic SELECT Statement

SELECT select_list
[ FROM table_source ]
[ WHERE search_condition ]
[ GROUP BY group_by_expression ]
[ HAVING search_condition ]
[ ORDER BY order_expression [ ASC | DESC ] ]

WHERE Conditions

-- AND
SELECT column_name FROM table_name
WHERE condition1 AND condition2

-- OR
SELECT column_name FROM table_name
WHERE condition1 OR condition2

-- EXISTS
SELECT column_name FROM table_name
WHERE EXISTS (SELECT column_name FROM table_name)

-- ANY
SELECT column_name FROM table_name
WHERE column = ANY (SELECT column_name FROM table_name)

-- ALL
SELECT column_name FROM table_name
WHERE column = ALL (SELECT column_name FROM table_name)

-- WHERE NOT
SELECT column_name FROM table_name
WHERE NOT condition

CASE Statement

CASE
    WHEN condition THEN 'true'
    ELSE 'false'
END

INSERT INTO Table

Specify columns

INSERT INTO table_name (column, column)
VALUES (value, value)

Insert to all columns

INSERT INTO table_name
VALUES (value, value)

UPDATE Table

UPDATE table_name
    SET column = value,
        column = value,
        column = value
WHERE condition;

DELETE Table

DELETE FROM table_name WHERE condition;

TRUNCATE Table

TRUNCATE TABLE table_name;

Basic Functions

SELECT TOP

SELECT TOP [ number | percent ] column_name
FROM table_name
WHERE condition;

MIN/MAX

Returns the smallest/biggest value in selected column

SELECT [ MIN | MAX ] (column_name)
FROM table_name
WHERE condition;

COUNT/AVG/SUM

SELECT [ COUNT | AVG | SUM] (column_name)
FROM table_name
WHERE condition;

LIKE Syntax

SELECT column
FROM table_name
WHERE column LIKE pattern;

pattern operator

WHERE column LIKE 'a%'	--Finds any values that start with "a"

WHERE column LIKE '%a' --Finds any values that end with "a"

WHERE column LIKE '%or%' --Finds any values that have "or" in any position

WHERE column LIKE '_r%' --Finds any values that have "r" in the second position

WHERE column LIKE 'a_%_%' --Finds any values that start with "a" and are at least 3 characters in length

WHERE column LIKE 'a%o' --Finds any values that start with "a" and ends with "o"

STUFF

The STUFF() function deletes a part of a string and then inserts another part into the string, starting at a specified position

-- Syntax
STUFF (character_expression, start, length, new_string )

-- Example: deletes the second digit of the product ID in the Productstable and replaces it with the characters '000'
SELECT STUFF([Product_ID], 2,1, '000')
FROM Products
-- OUTPUT: 20 becomes 2000

REPLACE

-- Syntax
REPLACE(string, old_string, new_string)

-- Replaces 'A' with 'C'
SELECT REPLACE('AB AB', 'A','C')

COALESCE

Returns the first non-null value in a list:

SELECT COALESCE(NULL, NULL, NULL, 'JigJun', NULL, 1);
-- OUTPUT: 'JigJun'

JOINS

Different types of JOINS

(INNER) JOIN: Returns records that have matching values in both tables
LEFT (OUTER) JOIN: Return all records from the left table, and the matched records from the right table
RIGHT (OUTER) JOIN: Return all records from the right table, and the matched records from the left table
FULL (OUTER) JOIN: Return all records when there is a match in either left or right table

SELECT column_name(s)
FROM table A
JOIN table B
    ON A.column_name = B.column_name;

SQL Statements

CREATE Table

CREATE TABLE table_name (
    column int IDENTITY(1,1) PRIMARY KEY, -- primary key and "IDENTITY(1,1)" for auto increment
    column data_type NOT NULL,            -- normal column
    column data_type NOT NULL FOREIGN KEY REFERENCES table_name(column) -- foreign key
);

ALTER Table

-- ADD Column
ALTER TABLE table_name
ADD column_name datatype;

-- DROP COLUMN
ALTER TABLE table_name
DROP COLUMN column_name datatype;

-- ALTER COLUMN
ALTER TABLE table_name
ALTER COLUMN column_name datatype;

CHECK Constraint

-- The CHECK constraint is used to limit the value range that can be placed in a column
CREATE TABLE table_name (
    ID int NOT NULL,
    [Percentage] DECIMAL(5,4),
    CHECK ([Percentage] <= 1.0000)
);

DEFAULT Constraint

-- DEFAULT constraint is used to provide a default value for a column
CREATE TABLE table_name (
    ID int NOT NULL,
    VARCHAR_column varchar(255) DEFAULT 'Text',
    INT_column INT DEFAULT 1
);

IF ELSE Statement

IF (@variable = 1)
BEGIN
    --insert code here
END
ELSE
BEGIN
    --insert code here
END

Declare Temporary Table

DECLARE @Temp TABLE
    (
        column INT,
        column2 VARCHAR(10)
    );

Stored Procedure Template (GET)

SET QUOTED_IDENTIFIER ON
SET ANSI_NULLS ON
GO

/******************************************************************************
** Change History
**
** CID    Date				Author			Description
** -----  ---------- ---------- -----------------------------------------------
** CH001  08/10/2019		N.Sun		    Initial Version
*******************************************************************************/
-- exec [SP_Template_Get] 1
CREATE PROCEDURE [dbo].[SP_Template_Get]
	@Parameter INT,
  @PageNumber INT = 1,
  @PageSize INT = 20,
AS
BEGIN
    DECLARE @Result TABLE
    (
        column INT,
        column2 VARCHAR(10)
    );

	INSERT INTO @Result
	(
	    column,
		column2,
	)
	SELECT column,
		   @column2
	FROM dbo.table_name A
	INNER JOIN dbo.table_name B
        ON A.column = B.column
	WHERE A.column = @Parameter

	SELECT
        column,
        column2
	FROM @Result
  ORDER BY
      CASE WHEN @SortingMode = 'DateAsc' THEN SampleDateColumn END ASC,
      CASE WHEN @SortingMode = 'DateDesc' THEN SampleDateColumn END DESC
  OFFSET ((@PageNumber - 1) * COALESCE(@PageSize, @PageCount)) ROWS
      FETCH NEXT COALESCE(@PageSize, @PageCount) ROWS ONLY
END;

GO

Stored Procedure Template (SET)

SET QUOTED_IDENTIFIER ON
SET ANSI_NULLS ON
GO

/******************************************************************************
** Change History
**
** CID    Date				Author			Description
** -----  ---------- ---------- -----------------------------------------------
** CH001  08/10/2019		N.Sun		    Initial Version
*******************************************************************************/
-- exec [SP_Template_Set] 1
CREATE PROCEDURE [dbo].[SP_Template_Set]
	@Parameter INT
AS
BEGIN
     BEGIN TRY
        BEGIN TRANSACTION

        -- Do something here

        COMMIT TRANSACTION
        SELECT 1 As Success
    END TRY
    BEGIN CATCH

        ROLLBACK TRANSACTION
        SELECT 0 As Success
    END CATCH
END;

GO

Common Table Expression (CTE)

-- Specifies a temporary named result set, known as a common table expression (CTE).
-- This is derived from a simple query and defined within the execution scope of a single SELECT, INSERT, UPDATE, or DELETE statement.


-- Defining the column list is optional
WITH CTE_Name (column1, column2)
AS
-- Define the CTE query.
(
    SELECT column1, column2
    FROM Table1
    WHERE column1 IS NOT NULL
)
-- Define the outer query referencing the CTE name.
SELECT *
FROM CTE_Name
GROUP BY column1, column2
ORDER BY column1, column2;
GO

Finding text in SP

SET QUOTED_IDENTIFIER ON
SET ANSI_NULLS ON
GO

CREATE PROCEDURE [dbo].[Find_Text_In_SP]
	@StringToSearch VARCHAR(100),
	@StringToSearch2 VARCHAR(100) = '',
	@StringToSearch3 VARCHAR(100) = '',
	@Name VARCHAR(100) = ''

AS

	SET @StringToSearch = '%' +@StringToSearch + '%'
	SET @StringToSearch2 = '%' +@StringToSearch2 + '%'
	SET @StringToSearch3 = '%' +@StringToSearch3 + '%'
	SET @Name = '%' +@Name + '%'

	SELECT ROUTINE_NAME, LEN(OBJECT_DEFINITION(OBJECT_ID(ROUTINE_NAME))) AS SP_Length
		FROM INFORMATION_SCHEMA.ROUTINES
	WHERE OBJECT_DEFINITION(OBJECT_ID(ROUTINE_NAME)) LIKE @stringtosearch
		AND OBJECT_DEFINITION(OBJECT_ID(ROUTINE_NAME)) LIKE @StringToSearch2
		AND OBJECT_DEFINITION(OBJECT_ID(ROUTINE_NAME)) LIKE @StringToSearch3
		AND (ROUTINE_TYPE='PROCEDURE' OR ROUTINE_TYPE='FUNCTION')
		AND ROUTINE_NAME LIKE @Name
	ORDER BY routine_name

GO

OFFSET FETCH Clause

-- Skip first 10 rows from the sorted result set and return the remaining rows.
SELECT column1, column2 FROM table_name ORDER BY column1 OFFSET 10 ROWS;

-- Skip first 10 rows from the sorted resultset and return next 5 rows.
SELECT column1, column2 FROM table_name ORDER BY column1 OFFSET 10 ROWS FETCH NEXT 5 ROWS ONLY;

Renaming a Table

exec sp_rename '[schema.old_table_name]', 'new_table_name'

Renaming a Column

exec sp_rename 'table_name.[oldColumName]' , 'newColumName', 'COLUMN'

SCOPE_IDENTITY

-- returns the last IDENTITY value inserted into an IDENTITY column in the same scope
-- returns the last identity value generated for any table in the current session and the current scope
-- A scope is a module; a Stored Procedure, trigger, function, or batch

SELECT SCOPE_IDENTITY()

FIND WHICH TABLE A CONSTRAINT BELONGS TO

SELECT
   OBJECT_NAME(o.parent_object_id)
FROM
   sys.objects o
WHERE
   o.name = 'MyConstraintName' AND o.parent_object_id <> 0

TRY-CATCH STATEMENT

BEGIN TRY
    BEGIN TRANSACTION

    -- Do something here

    COMMIT TRANSACTION
END TRY
BEGIN CATCH
    DECLARE
        @ErrorMessage NVARCHAR(4000),
        @ErrorSeverity INT,
        @ErrorState INT;
    SELECT
        @ErrorMessage = ERROR_MESSAGE(),
        @ErrorSeverity = ERROR_SEVERITY(),
        @ErrorState = ERROR_STATE();
    RAISERROR (
        @ErrorMessage,
        @ErrorSeverity,
        @ErrorState
        );

    ROLLBACK TRANSACTION
END CATCH

OPTIONAL CONDITION VARIABLES IN WHERE CLAUSE

-- using '=' operator
WHERE Column = IIF(@Variable IS NULL ,@Variable, Column)

-- using 'LIKE, IN, etc.'
WHERE (@Variable IS NULL OR Column LIKE '%' + @Variable + '%' )

INSERT COMMA SEPARATED STRING TO A TABLE

DECLARE @String = '1, 4, 3'
DECLARE @Tbl TABLE(ID INT);

INSERT INTO @Tbl
(
    ID
)
(SELECT value
FROM STRING_SPLIT(@String, ',')
WHERE RTRIM(value) <> '');

UPDATE WITH JOIN

UPDATE Table1
SET Table1.Column = B.Column
FROM Table1 A
    INNER JOIN Table2 B
        ON A.ID = B.ID

DELETE WITH JOIN

DELETE A
FROM Table1 A
INNER JOIN Table2 B
  ON B.Id = A.Id
WHERE A.Column = 1 AND B.Column = 2

UPDATE/INSERT IDENTITY COLUMN

SET IDENTITY_INSERT YourTable ON

   -- UPDATE/INSERT STATEMENT HERE

SET IDENTITY_INSERT YourTable OFF

Find Foreign Key constraint references of a table

SELECT
   OBJECT_NAME(f.parent_object_id) TableName,
   COL_NAME(fc.parent_object_id,fc.parent_column_id) ColName
FROM
   sys.foreign_keys AS f
INNER JOIN
   sys.foreign_key_columns AS fc
      ON f.OBJECT_ID = fc.constraint_object_id
INNER JOIN
   sys.tables t
      ON t.OBJECT_ID = fc.referenced_object_id
WHERE
   OBJECT_NAME (f.referenced_object_id) = 'Table_Name'

Parse a JSON file into a table

-- JSON Data sample:
-- {
-- "label": "test ",
-- "value": 1
-- },
-- {
-- "label": "test2 ",
-- "value": 2
-- }

DECLARE @tbl TABLE (id INT, label VARCHAR(500));

DECLARE @json VARCHAR(max);

SELECT @json = BulkColumn
 FROM OPENROWSET (BULK 'C:\jsonFile.json', SINGLE_CLOB) as j


 INSERT INTO @tbl (id, label)
 SELECT [value], label
 FROM OPENJSON(@json)
 WITH ([value] int,
       label nvarchar(max))

SELECT * FROM @tbl

Add FK to existing column

ALTER TABLE [Table1]
ADD CONSTRAINT FK_Table2_Id FOREIGN KEY (Table1_Id)
    REFERENCES Table2(Table2_Id);

List all user defined functions by type

SELECT [Name], [Definition], [Type_desc]
  FROM sys.sql_modules m
INNER JOIN sys.objects o
        ON m.object_id=o.object_id
WHERE [Type_desc] like '%function%'

UPDATE and REPLACE part of a string

UPDATE dbo.[Table]
SET Value = REPLACE(Value, '123\', '')
WHERE ID <=4

Generate random INT number

---- Create the variables for the random number generation
DECLARE @Random INT;
DECLARE @Upper INT;
DECLARE @Lower INT

---- This will create a random number between 1 and 999
SET @Lower = 1 ---- The lowest random number
SET @Upper = 999 ---- The highest random number
SELECT @Random = ROUND(((@Upper - @Lower -1) * RAND() + @Lower), 0)
SELECT @Random

Generate random DATES between two range

DECLARE @FromDate DATE = '2019-09-01';
DECLARE @ToDate DATE = '2019-12-31';

SELECT DATEADD(DAY, RAND(CHECKSUM(NEWID()))*(1+DATEDIFF(DAY, @FromDate, @ToDate)), @FromDate)

Get list of all tables in a database

SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE='BASE TABLE'

Check if a table exists in a database

IF EXISTS(SELECT *  FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'dbo' AND TABLE_NAME = 'Table')
BEGIN
  -- exists
END

Generate 6 unique digit number

SELECT LEFT(CAST(RAND()*1000000000+999999 AS INT),6) AS OTP

Search table name

SELECT * FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME LIKE '%%'

Search between two dates

--convert to date to ignore time
SELECT * FROM Table T
WHERE CONVERT(DATE,T.DateColumn) BETWEEN COALESCE(CONVERT(DATE,@DateFrom), CONVERT(DATE,T.DateColumn)) AND COALESCE(CONVERT(DATE,@DateTo), CONVERT(DATE,T.DateColumn))

Dates format

--Output: 21/03/2018
SELECT FORMAT (getdate(), 'dd/MM/yyyy ') as date

--Output: 21/03/2018, 11:36:14
SELECT FORMAT (getdate(), 'dd/MM/yyyy, hh:mm:ss ') as date

--Output: Wednesday, March, 2018
SELECT FORMAT (getdate(), 'dddd, MMMM, yyyy') as date

--Output: Mar 21 2018
SELECT FORMAT (getdate(), 'MMM dd yyyy') as date

--Output: 03.21.18
SELECT FORMAT (getdate(), 'MM.dd.yy') as date

--Output: 03-21-18
SELECT FORMAT (getdate(), 'MM-dd-yy') as date

--Output: 11:36:14 AM
SELECT FORMAT (getdate(), 'hh:mm:ss tt') as date

--Output: 03/21/2018
SELECT FORMAT (getdate(), 'd','us') as date

Triggers

create trigger t1 on table1
after insert
as
begin
    insert into Audit
    (Column)
    select 'Insert New Row with Key' + cast(t.Id as nvarchar(10)) + 'in table1'
    from table1 t where Id IN (select Id from inserted)
end
go

Find all tables containing column with specified name

SELECT      c.name  AS 'ColumnName'
            ,t.name AS 'TableName'
FROM        sys.columns c
JOIN        sys.tables  t   ON c.object_id = t.object_id
WHERE       c.name LIKE '%COLUMN_NAME%'
ORDER BY    TableName
            ,ColumnName;

Script to generate drop all tables with prefix

SELECT 'DROP TABLE ' + TABLE_NAME + '' 
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_NAME LIKE 'PREFIX_%'

Generate script to alter tables to remove all constraints

(uncomment EXEC to execute script, PRINT is for reference only)

DECLARE @SQL varchar(4000)=''
SELECT @SQL = 
@SQL + 'ALTER TABLE ' + s.name+'.'+t.name + ' DROP CONSTRAINT [' + RTRIM(f.name) +'];' + CHAR(13)
FROM sys.Tables t
INNER JOIN sys.foreign_keys f ON f.parent_object_id = t.object_id
INNER JOIN sys.schemas     s ON s.schema_id = f.schema_id
WHERE t.name LIKE 'PREFIX_%'

--EXEC (@SQL)

PRINT @SQL

Cursor Sample

Loop through a set of data

-- two variables to hold product name and list price (gonna be used on the loop)
DECLARE 
    @product_name VARCHAR(MAX), 
    @list_price   DECIMAL; 

--defines the result set for the cursor
DECLARE cursor_product CURSOR 
FOR SELECT 
        product_name, 
        list_price
    FROM 
        dbo.products; 

-- open cursor
OPEN cursor_product;

--fetch a row from the cursor into one or more variables
FETCH NEXT FROM cursor_product INTO 
    @product_name, 
    @list_price;

-- loop through the cursor
WHILE @@FETCH_STATUS = 0
    BEGIN
        -- use current product_name and list_price from current index of the cursor in the loop
        PRINT @product_name + CAST(@list_price AS varchar);
        -- fetch next row from the cursor
        FETCH NEXT FROM cursor_product INTO 
            @product_name, 
            @list_price;
    END;

-- close cursor
CLOSE cursor_product;

-- deallocate the cursor to release it
DEALLOCATE cursor_product;

sql-cheatsheet

Basic SELECT Statement

WHERE Conditions

CASE Statement

INSERT INTO Table

Specify columns

Insert to all columns

UPDATE Table

DELETE Table

TRUNCATE Table

Basic Functions

SELECT TOP

MIN/MAX

COUNT/AVG/SUM

LIKE Syntax

pattern operator

STUFF

The STUFF() function deletes a part of a string and then inserts another part into the string, starting at a specified position

REPLACE

COALESCE

Returns the first non-null value in a list:

JOINS

Different types of JOINS

SQL Statements

CREATE Table

ALTER Table

CHECK Constraint

DEFAULT Constraint

IF ELSE Statement

Declare Temporary Table

Stored Procedure Template (GET)

Stored Procedure Template (SET)

Common Table Expression (CTE)

Finding text in SP

OFFSET FETCH Clause

Renaming a Table

Renaming a Column

SCOPE_IDENTITY

FIND WHICH TABLE A CONSTRAINT BELONGS TO

TRY-CATCH STATEMENT

OPTIONAL CONDITION VARIABLES IN WHERE CLAUSE

INSERT COMMA SEPARATED STRING TO A TABLE

UPDATE WITH JOIN

DELETE WITH JOIN

UPDATE/INSERT IDENTITY COLUMN

Find Foreign Key constraint references of a table

Parse a JSON file into a table

Add FK to existing column

List all user defined functions by type

UPDATE and REPLACE part of a string

Generate random INT number

Generate random DATES between two range

Get list of all tables in a database

Check if a table exists in a database

Generate 6 unique digit number

Search table name

Search between two dates

Dates format

Triggers

Find all tables containing column with specified name

Script to generate drop all tables with prefix

Generate script to alter tables to remove all constraints

(uncomment EXEC to execute script, PRINT is for reference only)

Cursor Sample

Loop through a set of data

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