Like

The LIKE operator is another extremely powerful tool to help you define your search. In its most simple form, the LIKE operator functions just like the "=" operator. That is, it matches for equality in the WHERE clause. Thus, if we were to search our EMPLOYEES table, the statement:

    SELECT EMP_NAME, EMP_NUM 
    FROM EMPLOYEES
    WHERE EMP_NAME = 'Lim Sing Yuen';

would be the same as saying:

    SELECT EMP_NAME, EMP_NUM 
    FROM EMPLOYEES
    WHERE EMP_NAME LIKE 'Lim Sing Yuen';

In either case, you would get:

    EMP_NAME		EMP_NUM
    -------------------------------
    Lim Sing Yuen	002
    -------------------------------

However, the real umph of the LIKE operator comes from its ability to incorporate wildcards. Specifically, the LIKE operator can be used with the "%" and the "_" operator. The "%" operator can be used to match any string of any length and the "_" operator is used to match any single character. But this is best seen by example. Consider the following:

    SELECT EMP_NAME, EMP_NUM 
    FROM EMPLOYEES
    WHERE EMP_NAME LIKE 'Lim%';

In this case, you would get the following:

    EMP_NAME		EMP_NUM
    -------------------------------
    Lim Li Chuen	001
    Lim Sing Yuen	002
    -------------------------------

Notice that in both cases, the search string begins with "Lim". The "%" wildcard specifies that so long as the string begins with the string "Lim", it matches.

Consider the "_" operator.

    SELECT EMP_NAME, EMP_NUM 
    FROM EMPLOYEES
    WHERE EMP_NUM LIKE '00_';

In this case, you would get all the records returned that included a "00" followed by any other character:

    EMP_NAME	  	EMP_NUM
    -------------------------------
    Lim Li Chuen	001
    Lim Sing Yuen	002
    Loo Soon Keat	003
    -------------------------------

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