You can use the following SQL query to change the column of the table as case-sensitive:
ALTER TABLE a_table
ALTER COLUMN column_name VARCHAR(200)
COLLATE SQL_Latin1_General_CP1_CS_AS
And, if you wish to change the column to case insensitive, you can use the following SQL query:
ALTER TABLE a_table
ALTER COLUMN column_name VARCHAR(200)
COLLATE SQL_Latin1_General_CP1_CI_AS
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