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Tip of the Day
Language: Relational Databases
Expertise: Beginner
Jun 15, 1998

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Application Security Testing: An Integral Part of DevOps


Max Calculation

Question:
How do you select the maximum value of a column in a DBGrid when displayed through a query?

(query SQL:select max(CustNo) from customer, and get error message:"the table is read only")

Answer:
You have to go to the underlying table itself. You can't do this through a DBGrid. Remember, data control objects like TDBGrid are used purely for display and real-time editing. They don't really do any summarization.

But you can work around this by creating a calculated field that will perform the Max calculation for you in the OnCalcFields event. Read more about this in the online help.

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