SQL Expressions Expressions are used in the Where clauses, Having clauses, and Order By clauses of SQL Select statements. Expressions enable you to use mathematical operations as well as character string and date manipulation operators to form complex database queries. The most common expression is a simple field name. You can combine a field name with other expression elements. Valid expression elements are as follows: • Field Names • Constants • Exponential notation • Numeric operators • Character operators • Date operators • Relational operators • Logical operators • Functions Constants Exponential Notation Numeric Operators Character Operators Date Operators Relational Operators Logical Operators Operator Precedence Functions