How to Convert mmddyyyy varchar to datetime in SQL Server?

Converting mmddyyyy varchar to datetime in SQL Server

SQL Server database users often encounter the challenge of converting varchar strings representing dates (in mmddyyyy format) into the datetime data type. A direct conversion using CONVERT frequently fails due to out-of-range values. This guide provides a reliable solution.

The process involves these key steps:

1. String Preparation: First, declare a variable (e.g., @Date) of type char(8) and assign your mmddyyyy string to it. This ensures consistent string length.

2. String Manipulation: Utilize string functions (LEFT, RIGHT, SUBSTRING) to rearrange the string components into a yyyymmdd format, which SQL Server readily understands. Extract the year, month, and day portions individually and concatenate them in the correct order.

3. Conversion: Finally, use the CONVERT function to transform the rearranged string into a datetime data type.

Example:

The following SQL code demonstrates the conversion:

<code class="language-sql">DECLARE @Date char(8);
SET @Date = '12312009';
SELECT CONVERT(datetime, RIGHT(@Date, 4) + LEFT(@Date, 2) + SUBSTRING(@Date, 3, 2));</code>

This will output:

<code>-----------------------
2009-12-31 00:00:00.000
(1 row(s) affected)</code>

This method effectively handles the conversion, enabling further date-related operations within your SQL Server database. Remember to adapt the @Date variable to your specific varchar date string.

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