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Submitting a query for processing

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• Submitting a query for execution

  • Execute a query:

    // $conn = connection object returned by mysqli_connect( ) call if ( ( $result = mysqli_query( $conn, "SQL-command" ) ) == NULL ) { printf("Error: %s\n", mysqli_error($conn)); exit(1); } // $result = the result set object returned by the query

    Explanation:

    mysqli_query() will execute the SQL-command Return value of mysqli_query("query"): 0 (= False):   execution error Use mysqli_error() to get more information on the error a value ≠ 0:   a pointer to a mysqli_result object (= a set of tuples !!!)

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  • Example: using the mysqli_query( ) call

    /* ----------------------------------------- Make connection AND select "companyDB" ----------------------------------------- */ $conn = mysqli_connect("holland.mathcs.emory.edu","cs377", "abc123", "companyDB"); if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); exit(1); } /* ------------------------------------- Execute a select query ------------------------------------- */ $query = 'select fname, lname, salary from employee'; if ( ( $result = mysqli_query($conn, $query) ) == NULL ) { // Returned a NULL object -- error printf("Error: %s\n", mysqli_error($conn)); exit(1); } // We can retrieve the tuples in the result set using the $result variable !! // Discussed NEXT !