PHP —

MySQL Command Interpreter

The MySQL command interpreter is commonly used to create databases and tables in web database applications and to test queries. Throughout the remainder of this chapter we discuss the SQL statements for managing a database. All these statements can be directly entered into the command interpreter and executed. The statements can also be included in server-side PHP scripts, as discussed in later chapters.

Once the MySQL DBMS server is running, the command interpreter can be used. The command interpreter can be run using the following command from the shell, assuming you've created a user Alexa with a password shhh:

% /usr/local/bin/mysql -uAlexa -pshhh

The shell prompt is represented here as a percentage character, %.

Running the command interpreter displays the output:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 36 to server version: 3.22.38
Type 'help' for help.
mysql>

The command interpreter displays a mysql> prompt and, after executing any command or statement, it redisplays the prompt. For example, you might issue the statement:

mysql> SELECT NOW(  );

This statement reports the time and date by producing the following output:

+---------------------+
| NOW(  )               |
+---------------------+
| 2002-01-01 13:48:07 |
+---------------------+
1 row in set (0.00 sec)
mysql>

After running a statement, the interpreter redisplays the mysql> prompt. We discuss the SELECT statement later in this chapter.

As with all other SQL statements, the SELECT statement ends in a semicolon. Almost all SQL command interpreters permit any amount of whitespace-spaces, tabs, or carriage returns-in SQL statements, and they check syntax and execute statements only after encountering a semicolon that is followed by a press of the Enter key. We have used uppercase for the SQL statements throughout this tutorial. However, any mix of upper- and lowercase is equivalent.

On startup, the command interpreter encourages the use of the help command. Typing help produces a list of commands that are native to the MySQL interpreter and that aren't part of SQL. All non-SQL commands can be entered without the terminating semicolon, but the semicolon can be included without causing an error.