Cross Join

The¬†CROSS JOIN¬†joined every row from the first table (T1) with every row from the second table (T2). In other words, the cross join returns a Cartesian product of rows from both tables. In general, if the first table has n rows and the second table has m rows, the cross join will result in n... » read more


Use TRUNCATE instead of DELETE If you need to clear the data in a table, use TRUNCATE instead of DELETE. TRUNCATE lock the table instead of at each row. No triggers are activated and no logs are generated resulting in faster performance. Note: TRUNCATE TABLE will reset your identity to the initial seed, whereas DELETE... » read more

Sql Not Exist

The following SQL Server Not Exists query will find the Employees whose Occupation is neither Skilled Manual nor Clerical. Note: Using NOT EXISTS may have a performance hit. Try to use LEFT JOIN and WHERE column is NULL to test if there is a performance improvement. Sometimes, NOT EXISTS may be faster, and sometimes it... » read more