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Oracle: If Table Exists
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The best and most efficient way is to catch the "table not found" exception: this avoids the overhead of checking if the table exists twice; and doesn't suffer from the problem that if the DROP fails for some other reason (that might be important) the exception is still rai...
How can I find the data structure that represents mine layout of Minesweeper in memory?
...o play. Feed it with binary and it shows you everything. Like accelerators table for me.
alt text http://files.getdropbox.com/u/1478671/2009-07-29_161532.jpg
You can see here, that F2 button corresponds to 510 in wParam.
Now let's get back to code, that handles WM_COMMAND. It compares wParam wit...
How does Rails keep track of which migrations have run for a database?
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Rails creates a table in your database called schema_migrations to keep track of which migrations have run.
The table contains a single column, version. When Rails runs a migration, it takes the leading digits in the migration's file name a...
How to reset a single table in rails?
...rd::Base.connection.execute("DELETE from sqlite_sequence where name = 'yourtablename'")
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Altering a column: null to not null
I have a table that has several nullable integer columns. This is undesirable for several reasons, so I am looking to update all nulls to 0 and then set these columns to NOT NULL . Aside from changing nulls to 0 , data must be preserved.
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How to find all tables that have foreign keys that reference particular table.column and have values
I have a table whose primary key is referenced in several other tables as a foreign key. For example:
7 Answers
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What is a plain English explanation of “Big O” notation?
...billion operations per second).
If we use a simple structure called a hash table (an instant-speed lookup table, also known as a hashmap or dictionary), we pay a small cost by preprocessing everything in O(N) time. Thereafter, it only takes constant time on average to look up something by its key (i...
Query grants for a table in postgres
...dy found it:
SELECT grantee, privilege_type
FROM information_schema.role_table_grants
WHERE table_name='mytable'
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How to add a primary key to a MySQL table?
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After adding the column, you can always add the primary key:
ALTER TABLE goods ADD PRIMARY KEY(id)
As to why your script wasn't working, you need to specify PRIMARY KEY, not just the word PRIMARY:
alter table goods add column `id` int(10) unsigned primary KEY AUTO_INCREMENT;
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Set cellpadding and cellspacing in CSS?
In an HTML table, the cellpadding and cellspacing can be set like this:
28 Answers
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