# SQL syntax used in this manual

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 `|`. Has a special meaning in JDBC escape syntax (see JDBC escape syntax).
`( ) . ,` | 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 ]* )

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