How do i show values from the table-CodePudding

how do i show all values from this table

  ------ --------- ------- -------- ----- 
 | A    | B       | C     | D      | E   |
  ------ --------- ------- -------- ----- 
 |   2  |    K    | M     | NULL   | S   |
 |   3  |    L    | C     | NULL   | N   |
 |   4  |    R    | P     | NULL   | N   |
 |   5  |    P    | N     | C      | N   |
 |   6  |    Y    | Q     | NULL   | S   |
 |   7  |    S    | T     | NULL   | S   |
 |   8  |    C    | M     | NULL   | N   |
 |   9  |    X    | C     | NULL   | S   |
 |  10  |    E    | Q     | NULL   | N   |
 |  11  |    A    | C     | NULL   | S   |
 |  12  |    C    | NULL  | C      | N   |
 |  13  |    F    | Q     | NULL   | N   |
 |  14  |    L    | NULL  | C      | S   |
 |  15  |    S    | P     | NULL   | S   |
  ------ --------- ------- -------- -----

to this.
show the first 8 values from column A, B and the 7 will be 5 in column A

SELECT A, B FROM letters LIMIT 8;

 
  ------ -------- 
 | A    | B      |
  ------ -------- 
 |   2  |    K   |
 |   3  |    L   |
 |   4  |    R   |
 |   5  |    P   |
 |   6  |    Y   |
 |   5  |    S   |
 |   8  |    C   |
 |   9  |    X   |
  ------ --------

CodePudding user response：

You'll want to use a case expression or the if() function. My preference is a case expression because it's more portable. Furthermore you'll need to supply an ORDER BY clause since records in a table have no ordering.

SELECT CASE WHEN A=7 THEN 5 ELSE A END as A, B FROM letters ORDER BY letters.A LIMIT 8;