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I have a table with a column (int type) called age. This column should hold maximun value 50. If it exceeds then it shouldn't update that row.
Means this column shold take values from 0 to 50.
If I try to update that to 51 then that shouldn't allow.
Could any one help....!
736
To find the max value of a column, use the MAX() aggregate function; it takes as its argument the name of the column for which you want to find the maximum value. If you have not specified any other columns in the SELECT clause, the maximum will be calculated for all records in the table.
MAX can be used with numeric, character, and datetime columns, but not with bit columns.
To ask SQL Server about the minimum and maximum values in a column, we use the following syntax: SELECT MIN(column_name) FROM table_name; SELECT MAX(column_name) FROM table_name; When we use this syntax, SQL Server returns a single value. Thus, we can consider the MIN() and MAX() functions Scalar-Valued Functions.
The MAX() function returns the largest value of the selected column.
Try this:
CREATE TRIGGER check_trigger
BEFORE INSERT
ON table
FOR EACH ROW
BEGIN
IF NEW.age<0 OR NEW.age>50 THEN
CALL `Error: Wrong values for age`; -- this trick will throw an error
END IF;
END
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