how to compare textbox value with column's each value
Since you put very little effort into your question you only will get generalities:
Select the data you want to compare from your database. Use a loop to iterate over the returned records, and compare the value of the column in question to the value in your textbox.
However, if you just want to know if that value is in the database, you can use a where
clause to compare your textbox's value to the column in question. You may also want to look at like
.
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