SQL CONVERT Function

The SQL CONVERT function is one of the SQL Conversions Function used to convert an expression from one data type to another. If the SQL Server CONVERT function is unable to convert an expression into the desired data type, then it returns an Error.

For this SQL Server convert function demonstration, we are going to use the Employee table from the SQL Tutorial database.

SQL CONVERT Function Syntax

The basic syntax of the SQL Server CONVERT Function is as shown below:

CONVERT (Data_Type [(Length)], Expression, [Style])

-- For example
SELECT CONVERT (VARCHAR(50), 245) AS [result_name]
FROM [Source]

Data_Type: Here you have to specify the Data Type to which you want to convert an expression
Length: It is an optional parameter of integer type in SQL convert function. You can use this parameter to specify the length of the target data type. By default, it is 30.
Expression: Please specify any valid expression that you want to convert into the desired data type using SQL Server Convert function.
Style: It is also an optional parameter of integer type. You can use this parameter to define the style.

SQL CONVERT Function to format Date

The following are the list of formatting styles that are available in the SQL Server CONVERT function.

Without Century (yy)	With Century (yyyy)	Standard	Input/Output
–	0 to 100	This is the Default for both datetime, and smalldatetime	mon dd yyyy hh:miAM (or PM)
1	101	U.S.	1 = mm/dd/yy 101 = mm/dd/yyyy
2	102	ANSI	2 = yy.mm.dd 102 = yyyy.mm.dd
3	103	British/French	3 = dd/mm/yy 103 = dd/mm/yyyy
4	104	German	4 = dd.mm.yy 104 = dd.mm.yyyy
5	105	Italian	5 = dd-mm-yy 105 = dd-mm-yyyy
6	106	–	6 = dd mon yy 106 = dd mon yyyy
7	107	–	7 = Mon dd, yy 107 = Mon dd, yyyy
8	108	–	hh:mi:ss
–	9 or 109	Default + milliseconds	mon dd yyyy hh:mi:ss:mmmmAM (or PM)
10	110	USA	10 = mm-dd-yy 110 = mm-dd-yyyy
11	111	JAPAN	11 = yy/mm/dd 111 = yyyy/mm/dd
12	112	ISO	12 = yymmdd 112 = yyyymmdd
–	13 or 113	Europe Default + millisecond	dd mon yyyy hh:mi:ss:mmm(24h)
14	114	–	hh:mi:ss:mmm(24h)
–	20 or 120	ODBC canonical	yyyy-mm-dd hh:mi:ss(24h)
–	21 or 121	ODBC canonical with milliseconds. This is the Default for time, date, datetime2, and datetimeoffset	yyyy-mm-dd hh:mi:ss.mmm(24h)
–	126	ISO8601	yyyy-mm-ddThh:mi:ss.mmm (no Spaces)
–	127	ISO8601 with time zone Z	yyyy-mm-ddThh:mi:ss.mmmZ (no Spaces)
–	130	Hijri	dd mon yyyy hh:mi:ss:mmmAM
–	131	Hijri	dd/mm/yyyy hh:mi:ss:mmmAM

SQL CONVERT Example to Format DATE

In this example, we are going to use the CONVERT function on GETDATE() to return the date in different formats.

-- SQL SERVER CONVERT Function Example - Date Format
SELECT CONVERT(VARCHAR(50), GETDATE()) AS 'Result 1';

SELECT CONVERT(VARCHAR(50), GETDATE(), 100) AS 'Result 2';
SELECT CONVERT(VARCHAR(50), GETDATE(), 101) AS 'Result 3';
 
SELECT CONVERT(VARCHAR(50), GETDATE(), 102) AS 'Result 4';
SELECT CONVERT(VARCHAR(50), GETDATE(), 103) AS 'Result 5';
 
SELECT CONVERT(VARCHAR(50), GETDATE(), 104) AS 'Result 6';
SELECT CONVERT(VARCHAR(50), GETDATE(), 105) AS 'Result 7';
SELECT CONVERT(VARCHAR(50), GETDATE(), 110) AS 'Result 8';

OUTPUT

SQL CONVERT Money Format Example

If an expression is money or small money, then we can use the style argument to stylize. The following are the list of money formatting styles that are available in the SQL Server CONVERT function.

Value	Output
0	It will only return two digits after the decimal point
1	It will separate every three digits by placing a comma. It will also return two digits after the decimal point.
2	This return four digits after the decimal point
126	This is equivalent to 2 when you are converting to char, or varchar

-- SQL SERVER CONVERT Function Example - Date Format
DECLARE @Sale MONEY
SET @Sale = 1234567.98723

SELECT CONVERT(VARCHAR(50), @Sale) AS 'Result 1';

SELECT CONVERT(VARCHAR(50), @Sale, 0) AS 'Result 2';

SELECT CONVERT(VARCHAR(50), @Sale, 1) AS 'Result 3';
SELECT CONVERT(VARCHAR(50), @Sale, 2) AS 'Result 4';

SELECT CONVERT(VARCHAR(50), @Sale, 256) AS 'Result 5';

OUTPUT

SQL Convert float values Example

When an expression is float or real, we can use the style argument. The following are the list of formatting styles that are available in the SQL Server CONVERT function.

Value	Output
0	This return maximum of 6 digits
1	It returns eight digits. Always use in Scientific notation
2	It always returns 16 digits. Always use in Scientific notation
3	It is supported by SQL Server 2016. It returns 17 digits and is useful to perform the conversion without loosing

-- SQL SERVER CONVERT Function Example - Date Format
DECLARE @Sale FLOAT
SET @Sale = 1234567.98723

SELECT CONVERT(VARCHAR(50), @Sale) AS 'Result 1';

SELECT CONVERT(VARCHAR(50), @Sale, 0) AS 'Result 2';

SELECT CONVERT(VARCHAR(50), @Sale, 1) AS 'Result 3';
SELECT CONVERT(VARCHAR(50), @Sale, 2) AS 'Result 4';

SELECT CONVERT(VARCHAR(50), @Sale, 3) AS 'Result 5';

OUTPUT

SQL CONVERT Null Values Example 1

In this example, we will work with NULL values.

-- SQL SERVER CONVERT Function Example
DECLARE @str AS VARCHAR(50)
SET @str = NULL

SELECT CONVERT(INT, @str) AS Result;

SELECT CONVERT(INT, NULL) AS Result;

OUTPUT

Let us use what will happen if we used the Convert function to convert the ‘Tutorial Gateway’ string to date time. As you can see, it is not possible so, this function is returning Error as output.

-- SQL SERVER CONVERT Function Example
SELECT CONVERT(INT, 'Tutorial Gateway') AS Result;

OUTPUT

Sql Server CONVERT Function Example 3

In this example, we will apply the CONVERT function on our Employee table.

USE [SQL Tutorial]
GO
SELECT TOP 1000 [EmpID]
      ,[FirstName]
      ,[LastName]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome] AS [Yearly Income]
      ,CONVERT(VARCHAR(50),[Sales], 2) AS [Sale Amount]
      ,CONVERT(VARCHAR(50), [HireDate], 113) AS [Hire Date]
  FROM [Employee]

OUTPUT