sql server convert string to date with code examples

SQL Server provides several functions for converting strings to dates, including the CONVERT and CAST functions. These functions allow you to specify the format of the input string and the output date.

CONVERT Function

The CONVERT function can be used to convert a string to a date. The basic syntax of the CONVERT function is as follows:

CONVERT(data_type, expression, style)

The data_type argument specifies the data type to which the expression should be converted. For example, to convert a string to a date, you would use the data type 'date'. The expression argument is the string that you want to convert to a date. The style argument is optional and is used to specify the format of the input string.

For example, the following statement converts the string '2021-01-01' to a date:

SELECT CONVERT(date, '2021-01-01', 120) AS 'Date'

This statement returns the date '2021-01-01'.

You can also use the CONVERT function to convert a string to a specific date format. For example, the following statement converts the string '01/01/2021' to a date in the format 'yyyy-mm-dd':

SELECT CONVERT(date, '01/01/2021', 101) AS 'Date'

This statement returns the date '2021-01-01'.

CAST Function

The CAST function is similar to the CONVERT function and can also be used to convert a string to a date. The basic syntax of the CAST function is as follows:

CAST(expression AS data_type)

The expression argument is the string that you want to convert to a date, and the data_type argument specifies the data type to which the expression should be converted. For example, to convert a string to a date, you would use the data type 'date'.

For example, the following statement converts the string '2021-01-01' to a date:

SELECT CAST('2021-01-01' AS date) AS 'Date'

This statement returns the date '2021-01-01'.

In conclusion, CONVERT and CAST functions are the primary and most used functions to convert strings to dates in SQL Server. The choice between these two functions can be based on the user's preference or the specific version of SQL Server being used.

In addition to using the CONVERT and CAST functions to convert strings to dates in SQL Server, there are also several other built-in functions that can be used for date manipulation.

DATEADD Function

The DATEADD function is used to add a specified time interval to a date. The basic syntax of the DATEADD function is as follows:

DATEADD(interval, number, date)

The interval argument specifies the time interval to add, such as day, month, or year. The number argument is the number of intervals to add. The date argument is the date to which the interval will be added.

For example, the following statement adds 3 days to the date '2021-01-01':

SELECT DATEADD(day, 3, '2021-01-01') AS 'New Date'

This statement returns the date '2021-01-04'.

DATEDIFF Function

The DATEDIFF function is used to calculate the difference between two dates. The basic syntax of the DATEDIFF function is as follows:

DATEDIFF(interval, startdate, enddate)

The interval argument specifies the time interval to use for the calculation, such as day, month, or year. The startdate and enddate arguments are the two dates for which the difference will be calculated.

For example, the following statement calculates the number of days between the dates '2021-01-01' and '2021-01-10':

SELECT DATEDIFF(day, '2021-01-01', '2021-01-10') AS 'Days'

This statement returns the number of days 9.

DATEPART Function

The DATEPART function is used to extract a specific part of a date, such as the year, month, or day. The basic syntax of the DATEPART function is as follows:

DATEPART(interval, date)

The interval argument specifies the part of the date to extract, such as year, month, or day. The date argument is the date from which the part will be extracted.

For example, the following statement extracts the year from the date '2021-01-01':

SELECT DATEPART(year, '2021-01-01') AS 'Year'

This statement returns the year 2021.

FORMAT Function

SQL Server 2012 and later versions, the FORMAT function is used to format a date as a string. The basic syntax of the FORMAT function is as follows:

FORMAT(date, format)

The date argument is the date to be formatted, and the format argument is the format for the output string. The format codes for the date are similar to the codes used in the CONVERT and CAST functions.

For example, the following statement formats the date '2021-01-01' as a string in the format 'dd-MM-yyyy':

SELECT FORMAT( '2021-01-01', 'dd-MM-yyyy') as 'Formatted Date'

This statement returns the date '01-01-2021'

In conclusion, SQL Server provides a wide range of built-in functions to convert strings to dates, manipulate dates, extract parts of dates, and format dates as strings. These functions can be used in a variety of ways to perform tasks such as date calculations, date validation, and date formatting.

Popular questions

1. What is the basic syntax of the CONVERT function in SQL Server?
   Answer: The basic syntax of the CONVERT function in SQL Server is: CONVERT(data_type, expression, style) where data_type specifies the data type to which the expression should be converted, expression is the string that you want to convert to a date, and style is an optional argument used to specify the format of the input string.

2. How can you use the CONVERT function to convert a string to a specific date format in SQL Server?
   Answer: You can use the CONVERT function to convert a string to a specific date format by specifying the appropriate style code for the format. For example, to convert a string to a date in the format 'yyyy-mm-dd', you can use the following statement: SELECT CONVERT(date, '01/01/2021', 101) AS 'Date'

3. What is the difference between the CONVERT and CAST functions in SQL Server when converting strings to dates?
   Answer: Both the CONVERT and CAST functions can be used to convert strings to dates in SQL Server, but the CONVERT function provides more options for specifying the format of the input string. The CAST function has a simpler syntax, and can be used when you don't need to specify the format of the input string.

4. How can you use the DATEADD function in SQL Server to add a specified time interval to a date?
   Answer: You can use the DATEADD function in SQL Server to add a specified time interval to a date by providing the interval, number and date arguments. For example, to add 3 days to the date '2021-01-01', you can use the following statement: SELECT DATEADD(day, 3, '2021-01-01') AS 'New Date'

5. How can you use the DATEPART function in SQL Server to extract a specific part of a date?
   Answer: You can use the DATEPART function in SQL Server to extract a specific part of a date by providing the interval and date arguments. For example, to extract the year from the date '2021-01-01', you can use the following statement: SELECT DATEPART(year, '2021-01-01') AS 'Year'

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Dates.