1.10 Issuing Queries

1.10.1 Problem

You've started mysql and now you want to send queries to the MySQL server.

1.10.2 Solution

Just type them in, but be sure to let mysql know where each one ends.

1.10.3 Discussion

To issue a query at the mysql> prompt, type it in, add a semicolon ( ;) at the end to signify the end of the statement, and press Return. An explicit statement terminator is necessary; mysql doesn't interpret Return as a terminator because it's allowable to enter a statement using multiple input lines. The semicolon is the most common terminator, but you can also use \g ("go") as a synonym for the semicolon. Thus, the following examples are equivalent ways of issuing the same query, even though they are entered differently and terminated differently:

Example queries in this book are shown with SQL keywords like SELECT in uppercase for distinctiveness, but that's simply a typographical convention. You can enter keywords in any lettercase.

mysql> SELECT NOW( );
+---------------------+
| NOW( )               |
+---------------------+
| 2001-07-04 10:27:23 |
+---------------------+
mysql> SELECT
    -> NOW( )\g
+---------------------+
| NOW( )               |
+---------------------+
| 2001-07-04 10:27:28 |
+---------------------+

Notice for the second query that the prompt changes from mysql> to -> on the second input line. mysql changes the prompt this way to let you know that it's still waiting to see the query terminator.

Be sure to understand that neither the ; character nor the \g sequence that serve as query terminators are part of the query itself. They're conventions used by the mysql program, which recognizes these terminators and strips them from the input before sending the query to the MySQL server. It's important to remember this when you write your own programs that send queries to the server (as we'll begin to do in the next chapter). In that context, you don't include any terminator characters; the end of the query string itself signifies the end of the query. In fact, adding a terminator may well cause the query to fail with an error.