Difference between revisions of "SQL Syntax Considerations"

Revision as of 19:54, 1 February 2012

Considerations

SQL syntax is not case-sensitive, except for table names and field names.
Backticks are (`) are needed around any table or field name that is one of the SQL Reserved Words.

For example: SELECT * FROM `Order`

Without the backticks, you get an error like this:

Encountered "Order" at line column 15. Was expecting one of (...

That error means the parser found a word it recognized, but didn't find other things it expected before it got to that word.

When either a table name or a field name is reserved word, and both are used together, then backticks are needed around the combination.

For example: `Order.order_number`

If you do a query on different tables that have fields with the same name, you should provide column aliases for those fields. (Otherwise, a query for A.phone and B.phone identifies both sets of values as "phone". Column aliases make it possible to tell which table a set of values came from.)

Learn more: column_expr

@@ Line 18: / Line 18: @@
 ::which means that parser found a word it recognized, but didn't find other things it expected before it got to that word.
 -->
-:* If you do a query on different tables that have fields with the same name, you must provide  column aliases to identify those fields. (If you query A.phone and B.phone, both sets of values will be identified as "phone", unless you specify a column alias for at least one of them.)
+:* If you do a query on different tables that have fields with the same name, you should provide  column aliases for those fields. (Otherwise, a query for A.phone and B.phone identifies both sets of values as "phone". Column aliases make it possible to tell which table a set of values came from.)
 :: ''Learn more:'' [[#column_expr|column_expr]]