Can I set a formula for a particular column in SQL?

I want to implement something like Col3 = Col2 + Col1 i开发者_C百科n SQL.

This is somewhat similar to Excel, where every value in column 3 is sum of corresponding values from column 2 and column 1.

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Have a look at Computed Columns

A computed column is computed from an expression that can use other columns in the same table. The expression can be a noncomputed column name, constant, function, and any combination of these connected by one or more operators.

Also from CREATE TABLE point J

Something like

CREATE TABLE dbo.mytable 
( low int, high int, myavg AS (low + high)/2 ) ;

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Yes, you can do it in SQL using the UPDATE command:

UPDATE TABLE table_name
SET col3=col1+col2
WHERE <SOME CONDITION>

This assumes that you already have a table with populated col1 and col2 and you want to populate col3.

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Yes. Provided it is not aggregating data across rows.

assume that col1 and col2 are integers.

SELECT col1, col2, (col1 + col2) as col3 FROM mytable