SQL Basic Part-2

Some facts about Access queries:

• When table is opened in Design view, you cannot execute query related to the table.
• SQL Queries are NOT case sensitive.
• SQL queries can be written in free form way.
• SQL queries are terminated by semi-colon; but in MS-Access we need not have to do it.
• MS-Access provides its propriety clause TRANSFORM to create Two-Way table. It is not part of ANSI SQL.
• Domain function arguments are strings and hence they must be written inside double quotes.
• We should write Fields inside square brackets [] in QBE (Query-By-Example window), else errors may be generated. The reason is that the field without brackets is converted into strings surrounded by double quotes.
• To create field alias, we use AS keyword before the alias name.
• The alias should not be used in WHERE or HAVING clause etc because projection operation is done at last before the sorting operation while sub-setting operations occur before.
• The sorting operation used by help of ORDER BY clause is not part of SQL theory propounded by E.F. Codd. The reason is that ORDER BY operation on relation does not lead to any new relation. Simply the tuples are re-ordered. No new set is generated.
• In Access, TRUE and FALSE logical values are equivalent to -1 and 0. To convert -1 into 1, use ABS function.