• Text in this style  is used for variable input for which you should substitute a value of your own choosing. 

• Text in this style  is used for emphasis. 

• Text in this style  is used in table headings and to convey especially strong emphasis. 

• Text in this style  is used to indicate a program option that affects how the program is executed, or that supplies information that is needed for the program to function in a certain way. Example : “The -- host  option (short form -h ) tells the mysql  client program the hostname or IP address of the MySQL server that it should connect to” . 

•File names and directory names are written like this: “The global my.cnf  file is located in the /etc directory.” 

•Character sequences are written like this: “To specify a wildcard, use the ‘ % ’  character.” 

When commands are shown that are meant to be executed from within a particular program, the prompt shown preceding the command indicates which command to use. For example, shell>  indicates a command that you execute from your login shell, root-shell>  is similar but should be executed as root , and mysql>  indicates a statement that you execute from the mysql  client program: 

shell> type a shell command here root-shell> type a shell command as root  here mysql> type a mysql statement here 

In some areas different systems may be distinguished from each other to show that commands should be executed in two different environments. For example, while working with replication the commands might be prefixed with source  and replica : 

source> type a mysql command on the replication source here replica> type a mysql command on the replica here 

The “shell”  is your command interpreter. On Unix, this is typically a program such as sh , csh , or bash . On Windows, the equivalent program is command.com  or cmd.exe , typically run in a console window. 

When you enter a command or statement shown in an example, do not type the prompt shown in the example. 

Database, table, and column names must often be substituted into statements. To indicate that such substitution is necessary, this manual uses db_name , tbl_name , and col_name . For example, you might see a statement like this: 

mysql> SELECT col_name  FROM db_name . tbl_name ; 

This means that if you were to enter a similar statement, you would supply your own database, table, and column names, perhaps like this: 

mysql> SELECT author_name FROM biblio_db.author_list; 

SQL keywords are not case-sensitive and may be written in any lettercase. This manual uses uppercase. 

In syntax descriptions, square brackets (“ [ ”  and “ ] ” ) indicate optional words or clauses. For example, in the following statement, IF EXISTS  is optional: 

DROP TABLE [IF EXISTS] tbl_name 

When a syntax element consists of a number of alternatives, the alternatives are separated by vertical bars (“ | ” ). When one member from a set of choices may  be chosen, the alternatives are listed within square brackets (“ [ ”  and “ ] ” ): 

TRIM([[BOTH | LEADING | TRAILING] [ remstr ] FROM] str ) 

