The POSITION function searches for a string in a character value
    expression. The first character value expression is also called
    a search string. The second character value expression is also
    called a source string. If the search string is located, the
    POSITION function returns a numeric value that indicates the
    position of the search string in the source string. The returned
    numeric value is the absolute position of the search string in
    the source string starting with 1. The match between the search
    string and the source string is case sensitive.

    If the search string is not found in the source string, the
    POSITION function returns a zero (0)  value. If any of the
    strings is NULL, the result is NULL.

    The FROM clause of the POSITION function is an extension to the
    ANSI/ISO SQL standard and allows searching to begin from any
    location.

    Examples: Using the POSITION function

    Example 1: Using the POSITION function in a SELECT statement

    SQL> SELECT COLLEGE_NAME,
    cont> POSITION ('University' IN COLLEGE_NAME)
    cont> FROM COLLEGES
    cont> WHERE COLLEGE_NAME LIKE '_%University%';
     COLLEGE_NAME
     American University                  10
     Drew University                       6
     Harvard University                    9
     Purdue University                     8
     Stanford University                  10
     Yale University                       6
    6 rows selected

    Example 2: Using the POSITION function with the SUBSTRING clause

    SQL> SELECT SUBSTRING (COLLEGE_NAME FROM 1 FOR
    cont>                  POSITION ('University' IN COLLEGE_NAME) -1)
    cont> FROM COLLEGES
    cont> WHERE COLLEGE_NAME LIKE '_%University%';

     American
     Drew
     Harvard
     Purdue
     Stanford
     Yale
    6 rows selected

    Example 3: Using the POSITION function to find individual words.
    Because this example uses the TRACE statement, you must define
    the RDMS$DEBUG_FLAGS logical name to "Xt".

    SQL> BEGIN
    cont>   DECLARE :TXT VARCHAR(100);
    cont>   DECLARE :RES VARCHAR(20);
    cont>   DECLARE :ST, :EN INTEGER;
    cont> --
    cont>   SET :TXT = 'Some words and phrases';
    cont> --
    cont> --     Start at the beginning
    cont> --
    cont>   SET :ST = 1;
    cont> --
    cont> --     Loop over all the text looking for space delimiters
    cont> --
    cont>   WHILE :ST <= CHAR_LENGTH(:TXT)
    cont>   LOOP
    cont>     SET :EN = POSITION (' ' IN :TXT FROM :ST);
    cont>     IF :EN = 0 THEN
    cont> --
    cont> --     No trailing spaces, so assume space after last character
    cont> --
    cont>       SET :EN = CHAR_LENGTH(:TXT) + 1;
    cont>     END IF;
    cont>     SET :RES = SUBSTRING(:TXT FROM :ST FOR :EN - :ST);
    cont>     IF CHAR_LENGTH (TRIM (:RES)) > 0 THEN
    cont> --
    cont> --     Have a word to display
    cont> --
    cont>       TRACE 'Word: "', :RES, '"';
    cont>     END IF;
    cont> --
    cont> --     Advance the start position
    cont> --
    cont>     SET :ST = :EN + 1;
    cont>   END LOOP;
    cont> END;
    ~Xt: Word: "Some                "
    ~Xt: Word: "words               "
    ~Xt: Word: "and                 "
    ~Xt: Word: "phrases             "