SQL Programming

SQL statements can include programming elements just like most other programming languages. (You may want to see my section on Programming.)

• Developer Comments. Started by two dashes -- or enclosed by slash-asterisk /* and asterisk-slash */. MySQL uses -- (note the following space), /**/ and # (the latter is just like -- ).
• Statement Layout. Some specific to SQL-Transact.
  • Expressions. In SQL, an expression evaluates a single data value for each row in the result set. EG: SELECT ID, 1+2, price*2 FROM TableA. In most programming languages, expressions are symbols and operators that evaluate to a single data value. Expressions can include constants, functions that return one value, column references, or variables.
• Data Types. Each column, local variable, expression, and parameter has a related data type.
• Identifiers. Labels for database objects.
• Operators. Here is the precedence list in SQL Server:
  • Unary operators: + (Positive), - (Negative), ~ (Bitwise NOT)
  • Math  and string operators:
    • * (Multiply), / (Division), % (Modulo)
    • + (Add), (+ Concatenate), - (Subtract)
  • Comparison operators: =,  >,  <,  >=,  <=,  <>,  !=,  !>,  !<
  • Bitwise operators: ^ (Bitwise XOR), & (Bitwise AND), | (Bitwise OR)
  • Logical operators:
    • NOT
    • AND
    • ALL, ANY, BETWEEN, EXISTS, IN, LIKE, OR, SOME
  • Assignment operator: =
• Flow Control
• Functions
• Input/Output
• Program Halts
• Reserved Keywords. Certain keywords are reserved by SQL Server because they have particular use in T-SQL syntax.

There are four ways that multiple statements can be executed:

• Batches are non-compiled multiple statements sent to the server. (The end of a batch is signaled in SQL Server Query Analyzer, osql, and isql by use of the GO command.)
• Scripts are statements stored as files. Scripts usually consist of batches.
• Stored Procedures are pre-compiled statements on the server that can be called upon.
• Triggers are stored procedures that are not called but execute when certain events occur.

Page Modified: (Hand noted: 2007-10-12 21:25:46Z) (Auto noted: 2007-11-17 06:44:28Z)