# SQL syntax

SQL syntax is presented in modified BNF notation.

The meta-symbols of BNF are listed in the following table.

Table 1. BNF meta-symbols
Symbol | Meaning
--- | ---
`|` | Or. Choose one of the items.
`[ ]` | Encloses optional items.
`*` | Flags items that you can repeat 0 or more times. Has a special meaning in some SQL statements.
`{ }` | Groups required items so that they can be marked with the symbol `|`.
`( ) . ,` | Other punctuation that is part of the syntax.

The following example shows how SQL syntax is presented:

    CREATE [ UNIQUE ] INDEX indexName
      ON tableName ( simpleColumnName [ , simpleColumnName ]* )

Command-line syntax for running Java programs and utilities (as well as examples) always begins with the command java:

    java org.apache.derby.tools.ij

This documentation attempts to be JVM neutral, but any command line examples or syntax using JVM specific references should be verified with your JVM documentation.

Parent topic: Documentation conventions