Structured Query Language/Language Elements
SQL: The Standard ISO IEC 9075 and various Implementations Structured Query Language
Language Elements
Learning by Doing


SQL consists of statements which start with a key word like SELECT, DELETE or CREATE and terminate with a semicolon. Their elements are case-insensitive with the exception of fixed character string values like 'Mr. Brown'.

An example of a complete statement with several of its language elements.


  • Clauses: Statements are subdivided into clauses. The most popular one is the WHERE clause.
  • Predicates: Predicates specify conditions which can be evaluated to a boolean value. E.g.: a boolean comparison, BETWEEN, LIKE, IS NULL, IN, SOME/ANY, ALL, EXISTS.
  • Expressions: Expressions are numeric or string values by itself, or the result of arithmetic or concatenation operators, or the result of functions.
  • Object names: Names of database objects like tables, views, columns, functions.
  • Values: Numeric or string values.
  • Arithmetic operators: The plus sign, minus sign, asterisk and solidus (+, -, * and /) specify addition, subtraction, multiplication and division.
  • Concatenation operator: The '||' sign specifies the concatenation of character strings.
  • Comparison operators: The equals operator, not equals operator, less than operator, greater than operator, less than or equals operator, greater than or equals operator ( =, <>, <, >, <=, >= ) compares values and expressions.
  • Boolean operators: AND, OR, NOT combines boolean values.


SQL: The Standard ISO IEC 9075 and various Implementations Structured Query Language
Language Elements
Learning by Doing

  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.


Structured_Query_Language/Language_Elements
 

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