The WHERE clause will narrow the results of the selected table to whever the search_expression is true. The comparative operators will evaluate for numerical-numerical, datetime-datetime varchar-varchar combinations (where the codepage of the database determines the relative ordering), numerical-varchar, where the varchar will be type converted to a numeric type and datetime-varchar, where the varchar will be attempted to be type-converted to a datetime value. The same combinations can be used for the expression BETWEEN lower_expression AND upper_expression condition, which will return true only when expression lies exclusively between lower_expression and upper_expression. 

The LIKE term can match a string expression against a constant search string, in the standard SQL form. Ie. _ matches any single character and % matches any number of any character. Specifying NOT LIKE inverts the result. 

The IN search term will return true if the expression can be found within the single-column sub_select subquery given. Specifying NOT IN inverts the result.