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Da Notes -
70-029 - U
Personal notes on the MCDBA tests. These notes are from the various resources I used to pass the MCDBA exams including the MCDBA sample exams from Transcender. |
Passing Score: 693, Questions: 49, Time: 150 Min.
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Da Notes Index
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UNION
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Combine the result sets from two or more SELECT into one result set. The result sets must have the
same number of columns, same data types and same column order. E.g. NFC players and AFC
players tables could have a union to create a master NFL mailing list if both player tables have similar columns, data types, etc.
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UPDATE STATISTICS
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UPDATE STATISTICS tablename
Use this command so that all future T-SQL commands will build optimal query plans
UPDATE STATISTICS: against one table that you specify.
The stored proc SP_UPDATESTATS: executes UPDATE STATISTICS against every table in the current database.
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UPDLOCK
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Use update locks instead of shared locks while reading a table, and hold locks until the end of the statement or transaction.
UPDLOCK has the advantage of allowing you to read data (without blocking other readers) and update it later with the assurance that the data has not changed since you last read it.
To minimize deadlocks: Use resources in the same sequence in all transactions. Avoid user interaction in transactions. Keep transactions short and in one batch. Use as low isolation level as possible.
Severity:
1-10 Info
11-16 User generated
17-19 Hardware or software errors
20-25 Fatal. The client will be disconnected.
To be able to restore the database to a moment in time it must be possible to backup the active transaction log. This can only be done if the log and the primary data files can be reached. You should place the log and the primary data files on a mirror set.
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