selectstatement.htm

Absolute Database 5.12 src. Absolute Database lets you forget the Borland Database Engine (BDE). Th

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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000">
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">CROSS JOIN and INNER JOIN produce a simple Cartesian product, the same result as you get from listing the two items at the top level of FROM, but restricted by the join condition (if any). CROSS JOIN is equivalent to INNER JOIN ON (TRUE), that is, no rows are removed by qualification. These join types are just a notational convenience, since they do nothing you couldn't do with plain FROM and WHERE. 
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">LEFT OUTER JOIN returns all rows in the qualified Cartesian product (i.e., all combined rows that pass its join condition), plus one copy of each row in the left-hand table for which there was no right-hand row that passed the join condition. This left-hand row is extended to the full width of the joined table by inserting null values for the right-hand columns. Note that only the JOIN clause's own condition is considered while deciding which rows have matches. Outer conditions are applied afterwards. 
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">Conversely, RIGHT OUTER JOIN returns all the joined rows, plus one row for each unmatched right-hand row (extended with nulls on the left). This is just a notational convenience, since you could convert it to a LEFT OUTER JOIN by switching the left and right inputs.
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">FULL OUTER JOIN returns all the joined rows, plus one row for each unmatched left-hand row (extended with nulls on the right), plus one row for each unmatched right-hand row (extended with nulls on the left). 
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"></span></td></tr></table><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">ON <i>join_condition</i> 
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">join_condition is an expression resulting in a value of type boolean (similar to a WHERE clause) that specifies which rows in a join are considered to match.
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"></span></td></tr></table><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">USING (join_column [, ...]) 
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">A clause of the form USING ( a, b, ... ) is shorthand for ON left_table.a = right_table.a AND left_table.b = right_table.b .... Also, USING implies that only one of each pair of equivalent columns will be included in the join output, not both. 
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</span></td></tr></table><table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span></td></tr></table><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">NATURAL 
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">NATURAL is shorthand for a USING list that mentions all columns in the two tables that have the same names. 
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</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b>Example:
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span></span><span style="font-family:Courier New; font-size:8pt; color:#000000">SELECT&nbsp;Event_Name,&nbsp;Venue&nbsp;FROM&nbsp;Events&nbsp;e&nbsp;INNER&nbsp;JOIN&nbsp;Venues&nbsp;v&nbsp;ON&nbsp;(e.VenueNo=v.VenueNo)&nbsp;ORDER&nbsp;BY&nbsp;Event_Name
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</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b>WHERE Clause
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</b></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">The WHERE clause is used to specify the conditions any records returned by a query must satisfy.
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</i></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><i>condition</i> specifies the search conditions that will be used by the WHERE clause.  It is composed of one or more predicate expressions connected by the AND, NOT, and OR logical operators.
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</b></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b>Example:
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span></span><span style="font-family:Courier New; font-size:8pt; color:#000000">SELECT&nbsp;*&nbsp;FROM&nbsp;events&nbsp;WHERE&nbsp;Event_Name&nbsp;LIKE&nbsp;'%men%'
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<b>GROUP BY Clause
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</b></span><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"><b>
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</b></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">The GROUP BY clause segregates the output records into groups.  It is commonly used with the aggregate functions which calculate a value, such as a sum, for each group.
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When GROUP BY is present, it is not valid for the SELECT list expressions to refer to ungrouped columns except within aggregate functions, since there would be more than one possible value to return for an ungrouped column.
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</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b>Example:
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span></span><span style="font-family:Courier New; font-size:8pt; color:#000000">SELECT&nbsp;FirstName,&nbsp;COUNT(FirstName)&nbsp;FROM&nbsp;Employee&nbsp;GROUP&nbsp;BY&nbsp;FirstName
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<b>HAVING Clause
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</b></span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000">The HAVING clause is primarily used to impose search conditions onto the records returned by a GROUP BY clause.  
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When not used in conjunction with a GROUP BY clause, HAVING behaves like a WHERE clause.
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</span><span style="font-family:Helvetica,Arial; font-size:10pt; color:#000000"><b>Example:
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<table width="100%" border="0" cellpadding="0" cellspacing="0"><tr valign="top"><td width="14"></td><td><span style="font-family:Helvetica,Arial; font-size:4pt; color:#000000"></span></span><span style="font-family:Courier New; font-size:8pt; color:#000000">SELECT&nbsp;VenueNo,&nbsp;Avg(Ticket_Price)&nbsp;FROM&nbsp;events&nbsp;GROUP&nbsp;BY&nbsp;VenueNo&nbsp;HAVING&nbsp;Event_Date&nbsp;&lt;&nbsp;NOW