variable decimal places in sql

How do you make it so that all calculations in the DB compute to a pre-specified # of decimal places? Say I have three tables with the following fields

Table1

• A int
• B decimal(18, 3)

Table2

• A int
• B decimal (1开发者_StackOverflow社区8, 2)
• C decimal (18, 3)

Table3

• A int
• Precision int

Now I need to change it so that all my calculations are based on what precision is set for A in Table3. I started by converting all my decimals to decimal (30, 10) to allow for higher precisions if specified.

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Wrap your results in a CAST statement to set them to the desired precision. I.e.:

SELECT CAST((<query>) AS int) AS Result

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Try using the ROUND function in a stored procedure that first retrieves the precision from your Table3 table.