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Question 46: What does “SELECT 1;” actually do? – MySQL Question of the Day

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Question 46: What does “SELECT 1;” actually do?

21. May 2010
By plogi in mysql questions

1 Comment

In many of the questions selects without tables are used.
But what does “SELECT 1;” for example actually do?
 
(Pick 1 correct answer; or if you like a challenge try finding all)
 
a) It results in a syntax error of course!
b) With Oracle you write it like: “select 1 from dual;”
c) In DB2 you get the same result with “values 1;”.
d) The result will be 1 row with 1 column containing “1″.
 
[ Just for fun ]

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One Response

  1. plogi — 21. May 2010 @ 21:02:58 —


    b c d are correct.
    It works like selecting a constant from a table with 1 row.

    mysql> select 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.00 sec)

     
    Using the same technique, you can use MySQL as a pocket-calculator:

    select 230*12+1;

mysql> select 230*12+1;
+----------+
| 230*12+1 |
+----------+
|     2761 |
+----------+
1 row in set (0.02 sec)

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