# Chapter 9 Language Structure

**Table of Contents**

[9.1 Literal Values](literals.html)
[9.1.1 String Literals](string-literals.html)
[9.1.2 Numeric Literals](number-literals.html)
[9.1.3 Date and Time Literals](date-and-time-literals.html)
[9.1.4 Hexadecimal Literals](hexadecimal-literals.html)
[9.1.5 Bit-Value Literals](bit-value-literals.html)
[9.1.6 Boolean Literals](boolean-literals.html)
[9.1.7 NULL Values](null-values.html)
[9.2 Schema Object Names](identifiers.html)
[9.2.1 Identifier Length Limits](identifier-length.html)
[9.2.2 Identifier Qualifiers](identifier-qualifiers.html)
[9.2.3 Identifier Case Sensitivity](identifier-case-sensitivity.html)
[9.2.4 Mapping of Identifiers to File Names](identifier-mapping.html)
[9.2.5 Function Name Parsing and Resolution](function-resolution.html)
[9.3 Keywords and Reserved Words](keywords.html)
[9.4 User-Defined Variables](user-variables.html)
[9.5 Expressions](expressions.html)
[9.6 Query Attributes](query-attributes.html)
[9.7 Comments](comments.html)

 This chapter discusses the rules for writing the following elements of [SQL](glossary.html#glos_sql) statements when using MySQL:

* Literal values such as strings and numbers

* Identifiers such as database, table, and column names

* Keywords and reserved words

* User-defined and system variables

* Expressions

* Query attributes

* Comments

