How to Quantify Text Differences in TSQL

Compare text differences via T-SQL.

TSQL is a set of programming extensions to Structured Query Languages -- or SQL -- including transaction control, exception and error handling, and declared variables. Both Microsoft’s SQL Server and Sybase’s SQL server support T-SQL statements. SQL Server contains a selection of system data types used with the program -- including exact numeric, approximate numeric, data and time, and character strings. Character strings include two data types: char and varchar. T-SQL also has various functions such as Add, Subtract, Multiply, Divide, Break and Difference.

Things You'll Need

• TSQL

Instructions

1. Click “Start,” “All Programs” and “SQL Server Management Studio.” Click one of the databases on the Object Explorer to expand it. Right-click “Tables” and select “New Table.”

2. Specify the first column as “Item_ID” by entering it in the Column Name field. Select a data type for it such as “int” by clicking the drop-down options on the Data Type field. Create another column name “Item_Name” with “varchar” data type.

3. Click “File” and “Save Table_1” to save the table. Name the table as “items.” The data insertion interface is prompted. Enter data into the table such as “1” and “Computer” in the first row.

4. Click “New Query” to enter the query dialog. Enter the following T-SQL statement:
   SELECT DIFFERENCE (Items.Item_Name, “Components”)

5. Entering the code shown in Step 4 returns an integer value showing the difference between the Soundex values of the two string expressions. In this case, it will return a value of 3. The Soundex function returns a four-character code to assess the similarity of two strings.

References

• Microsoft.com: DIFFERENCE (Transact-SQL)
• Microsoft.com: Data Types (Transact-SQL)