SQL CAST Function

The SQL CAST function is mainly used to convert the expression from one data type to another data type. If the SQL Server CAST function is unable to convert a declaration to the desired data type, this function returns an error. We use the CAST function to convert numeric data into character or string data.

Syntax:

Here, the [data type] is a type of valid data types in RDBMS.

The syntax is:

CAST (EXPRESSION AS Data_ Type[(Length)]
_ _ CAST in the SQL example
SELECT CAST (123 AS VARCHAR (20)) [result_name]
FROM [Source]

Expression: It is a valid expression where we want to convert a data type into the SQL.
Data_type: It is a Data Type to which we want to convert the expression.
Length: It is the optional parameter of an integer type. We can use the setting to define the length of any targeted data type.

By default, it is 30.

Examples:

Here, we will use the below tables.

Table Manager _ Score

Column Name	Date Type
Manager Id	Integer
First _ Name	char( 20)
Score	float

The table contains the following rows:

Table Manager_Score

ManagerID	First_Name	Score
1	Jame	92.2
2	Boby	87.5
3	Marry	70
4	Sanju	120.2

Example 1:

SELECT First_Name, CAST (Score AS Integer)
Int_Score FROM Student_Score;

Result:

First_Name	Int_Score
Jame	92
Boby	87
Marry	70
sanju	120

In Example 1, we are using the CAST function to convert the SCORE column from type FLOAT to INTEGER. When we do it, various RDBMS have many rules to handle the numbers to the point of decimal.

According to the above example, the numbers after the decimal point are truncated.

Example 2:

SELECT First_Name, CAST (Score AS char (3))
Char_Score FROM Student_Score;

Result:

First__Name	Char__Score
Jame	85.
Boby	92.
Marry	90
sanju	110

In Example 2, we use the CAST function to convert the SCORE column from type FLOAT to CHAR (3). When we do it, we only hold the first 3 character. If there are more than three characters, everything after the first three characters is discarded.

Next TopicSQL Tutorial

← prev next →