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Should each and every table have a primary key?
I'm creating a database table and I don't have a logical primary key assigned to it. So, I'm thinking about leaving it without a primary key, but I'm feeling a bit guilty about it. Should I?
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You can't specify target table for update in FROM clause
I have a simple mysql table:
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Tables instead of DIVs [duplicate]
Under what conditions should you choose tables instead of DIVs in HTML coding?
24 Answers
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PostgreSQL function for last inserted ID
In PostgreSQL, how do I get the last id inserted into a table?
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Adding 'serial' to existing column in Postgres
I have a small table (~30 rows) in my Postgres 9.0 database with an integer ID field (the primary key) which currently contains unique sequential integers starting at 1, but which was not created using the 'serial' keyword.
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When increasing the size of VARCHAR column on a large table could there be any problems?
...er 2008 and I need to make a VARCHAR field bigger, from (200 to 1200) on a table with about 500k rows. What I need to know is if there are any issues I have not considered.
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What is the maximum length of a table name in Oracle?
What are the maximum length of a table name and column name in Oracle?
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How do I find which transaction is causing a “Waiting for table metadata lock” state?
I am trying to perform some DDL on a table and SHOW PROCESSLIST results in a " Waiting for table metadata lock " message.
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MySQL: #126 - Incorrect key file for table
...is can be caused by a full ramdisk when doing things like altering a large table if you have a ramdisk configured. You can temporarily comment out the ramdisk line to allow such operations if you can't increase the size of it.
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MySQL ON vs USING?
...fferences are noteworthy:
ON is the more general of the two. One can join tables ON a column, a set of columns and even a condition. For example:
SELECT * FROM world.City JOIN world.Country ON (City.CountryCode = Country.Code) WHERE ...
USING is useful when both tables share a column of the exac...