SQL DATE TIME Statement

SQL DATE statement

 

When working with SQL Date the most difficult part  is to be sure that the format of the date you are trying to insert, matches the format of the date column in the database in SQL Server

 

As long as your data contains only the date portion, your queries will work as expected. However, if a time portion is involved, it gets more complicated in SQL. 

 

The SQL Date defines a date that is combined with a time of day with fractional seconds that is based on a 24-hour clock

 

Note

Use the time date datetime2 and datetimeoffset data types for new work. These types align with the SQL standard

 

They are more portable times;  datetime2 and  datetimeoffset provide more seconds; and precisiondatetimeoffset provides time zone support for globally deployed applications

 

SQL Date data types

 

SQL Server - SQL Server comes with the following data types for storing a date or a date/time value in the database

• DATE - format YYYY-MM-DD
• DATETIME - format: YYYY-MM-DD HH:MI:SS
• SMALLDATETIME - format: YYYY-MM-DD HH:MI:SS
• TIMESTAMP - format: a unique number

The date types are chosen for a column when you create a new table in your database 

 

Working with Dates in SQL

 

You can compare two dates easily if there is no time component involved

 

We have the following OrderDetails  table 

 

Syntax 

Select * from OrderDetails

Example

 

 

Now we want to select the records with an OrderDate of 2019-04-11 from the table above

 

We use the following Select statement

Syntax 

SELECT FROM OrderDetails  WHERE OrderDate='2019-04-11'

Example 

 

 

 

Converting date and time data in SQL

 

Converting date and time data is when you convert to date and time data types, SQL server rejects all values.

 

It doesn't recognize as dates or times for information about using the cast and convert functions with date and time data, see cast and convert in SQL.

 

Converting date to other date and time types

This section describes what occurs when you convert a date data type to other date and time data types.

When the conversion is to time(n), the conversion fails, and error message 206 is raised and there is an operand type clash: date is incompatible with time.

If the conversion is to datetime, date is copied. The following code shows the results of converting a date value to a datetime value

 

Syntax 

DECLARE @date date = '12-21-16';
DECLARE @datetime datetime = @date;
SELECT @datetime AS '@datetime', @date AS '@date';

Example

 

 

The datetime is define when the conversion is from time(n),the time component is copied, and the date component is set to '1900-01-01'.

 

When the fractional precision of the time(n) value is greater than three digits, the value will be truncated to fit.

 

The following example shows the results of converting a time(4)value to a datetime value.

 

Syntax 

DECLARE @time time(4) = '12:10:05.1237';
DECLARE @datetime datetime = @time;
SELECT @datetime AS '@datetime', @time AS '@time';

Example

 

 

The SQL date time conversion is from smalldatetime the hours and minutes are copied. The seconds and fractional seconds are set to 0.

 

The following code shows the results of converting a smalldatetime value. 

 

Syntax

DECLARE @smalldatetime smalldatetime = '12-01-19 12:32';
DECLARE @datetime datetime = @smalldatetime;
SELECT @datetime AS '@datetime', @smalldatetime AS '@smalldatetime';

Example  

 

 

The SQL date time is defined as when the conversion is from datetimeoffset(n)the date and time components are copied.

 

The time zone is truncated. When the fractional precision of the datetimeoffset(n)value is greater than three digits, the value will be truncated.

 

The following example shows the results of converting a datetimeoffset(4) value to a datetime value.

 

Syntax  

DECLARE @datetimeoffset datetimeoffset(4) = '1968-10-23 12:45:37.1234 +10:0';
DECLARE @datetime datetime = @datetimeoffset;

SELECT @datetime AS '@datetime', @datetimeoffset AS '@datetimeoffset';

Example

 

 

The Datetime is defined as when the conversion is from <datetime2(n),the date="" and="" time="" are="" copied.="" when="" the="" fractional="" precision="" of="" the datetime2(n)<="" b=""> value is greater than three digits, the value will be truncated. </datetime2(n),the>

 

The Datetime is defined as when the conversion is from datetime2(n), the date and time are copied.

 

When the fractional precision of the datetime2(n) value is greater than three digits, the value will be truncated. 

 

The following example shows the results of converting a datetime2(4)value to a datetimevalue.

 

The following example shows datetime and datetime2 in SQL server 

 

Syntax

DECLARE @datetime2 datetime2(4) = '1968-10-23 12:45:37.1237';
DECLARE @datetime datetime = @datetime2;
SELECT @datetime AS '@datetime', @datetime2 AS '@datetime2';

Example 

The following example compares the results of casting a string to each date and  data type. 

 

Syntax

SELECT
     CAST'2019-05-18 12:35:29. 1234567 +12:15' AS  "keyword">time(7)) AS 'time'
    ,CAST'2019-05-18 12:35:29. 1234567 +12:15' AS date AS 'date'
    ,CAST('2019-05-18 12:35:29.123' >AS smalldatetime) AS
        'smalldatetime'
    ,CAST'2019-05-18 12:35:29.123' AS datetime) >AS 'datetime'
    ,CAST('2019-05-18 12:35:29. 1234567 +12:15'  >AS datetime2(7)) AS
        'datetime2'
    ,CAST'2019-05-18 12:35:29.1234567 +12:15' AS datetimeoffset(7)) AS
        'datetimeoffset';

Example

 

Summary

 

In this article, you learned how to use  SQL Date and Time Data with various options.