Tutorial by Examples: a
List partitioning is similar to range partitioning in many ways. As in partitioning by RANGE, each partition must be explicitly defined. The chief difference between the two types of partitioning is that, in list partitioning, each partition is defined and selected based on the membership of a colum...
Partitioning by HASH is used primarily to ensure an even distribution of data among a predetermined number of partitions. With range or list partitioning, you must specify explicitly into which partition a given column value or set of column values is to be stored; with hash partitioning, MySQL take...
The UNION operator is used to combine the result-set (only distinct values) of two or more SELECT statements.
Query: (To selects all the different cities (only distinct values) from the "Customers" and the "Suppliers" tables)
SELECT City FROM Customers
UNION
SELECT City FROM ...
UNION ALL to select all (duplicate values also) cities from the "Customers" and "Suppliers" tables.
Query:
SELECT City FROM Customers
UNION ALL
SELECT City FROM Suppliers
ORDER BY City;
Result:
Number of Records: 12
City
-------
Aachen
Albuquerque
Anchorage
Ann A...
UNION ALL to select all(duplicate values also) German cities from the "Customers" and "Suppliers" tables.
Here Country="Germany" is to be specified in the where clause.
Query:
SELECT City, Country FROM Customers
WHERE Country='Germany'
UNION ALL
SELECT City, Count...
Full width table cell background images
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Some email clients (notably Windows Desktop Outlook) collapse tables with no content, even if there are dimensions or padding.
To prevent these clients from collapsing the spacer table, you can add an invisible &nbsp; that serves as content. Then zero out the character's font-size and line-heig...
