The ISNUMERIC() function in SQL Server enables you to check whether or not an expression is numeric.

However, there may be times where you get results that you didn’t expect. This could happen if you have an expression that contains a character that is not a number, but is still accepted by ISNUMERIC() as being numeric.

There are a bunch of characters that ISNUMERIC() accepts as numeric that you might not have thought of as numeric. These include characters such as plus (+), minus (-), and the various currency symbols. Also, depending on its placement, the letter e could also allow the whole expression to be interpreted as numeric.

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In SQL Server, you can use the ISNUMERIC() function to find out whether an expression is numeric or not.

The function returns 1 if the expression is numeric, and 0 if it’s not.

To use this function, simply pass the value/expression to the function while calling it.

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In SQL Server, you can use the FILE_IDEX() function to return the ID of a given database file. You can also use the FILE_ID() function to do the same thing. Both functions serve pretty much the same purpose, so why does T-SQL have both functions?

It appears that FILE_IDEX() is a replacement for FILE_ID(), and it supports a larger range of file IDs. Microsoft now recommends against using FILE_ID(), as it’s in maintenance mode and may be removed in a future version of SQL Server.

So if you’re looking for a quick answer for which function to use, use FILE_IDEX().

But if you’re interested in the difference between these two functions, read on.

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In SQL Server, you can use the FILE_IDEX() function to return the ID of a given database file.

To do this, pass the logical file name of the database file to the function. This is the name that corresponds to the name column in the sys.master_files catalog view or the sys.database_files catalog view. Those views also contain the file ID, but FILE_NAME() saves you from having to query those views.

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In SQL Server, you can use the FILE_NAME() function to return the logical file name of a given database file.

To do this, pass the file ID to the function. This is the ID that corresponds to the file_id column in the sys.master_files catalog view or the sys.database_files catalog view. Those views also contain the logical file name, but the FILE_NAME() function saves you from having to query those views.

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You can use the OBJECTPROPERTY() function in SQL Server to check whether or not a table has a timestamp column.

To do this, pass the table’s object ID as the first argument, and TableHasTimestamp as the second argument. The function returns a 1 or a 0 depending on whether or not it has a timestamp column.

A return value of 1 means that the table does have a timestamp column, and a value of 0 means that doesn’t.

This also works for columns that have been defined as rowversion (timestamp is the deprecated synonym for rowversion).

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