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How to select all records from one table that do not exist in another table?
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SELECT t1.name
FROM table1 t1
LEFT JOIN table2 t2 ON t2.name = t1.name
WHERE t2.name IS NULL
Q: What is happening here?
A: Conceptually, we select all rows from table1 and for each row we attempt to find a row in table2 with the same value fo...
Disable Enable Trigger SQL server for a table
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use the following commands instead:
ALTER TABLE table_name DISABLE TRIGGER tr_name
ALTER TABLE table_name ENABLE TRIGGER tr_name
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Easiest way to rename a model using Django/South?
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To answer your first question, the simple model/table rename is pretty straightforward. Run the command:
./manage.py schemamigration yourapp rename_foo_to_bar --empty
(Update 2: try --auto instead of --empty to avoid the warning below. Thanks to @KFB for the tip.)
If ...
How do I search an SQL Server database for a string?
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This will search every column of every table in a specific database. Create the stored procedure on the database that you want to search in.
The Ten Most Asked SQL Server Questions And Their Answers:
CREATE PROCEDURE FindMyData_String
@DataToFind NVARCHAR(40...
Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server
...ossible to create a primary key or unique index within a SQL Server CREATE TABLE statement. Is it possible to create a non-unique index within a CREATE TABLE statement?
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What is the recommended way to delete a large number of items from DynamoDB?
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What I ideally want to do is call LogTable.DeleteItem(user_id) -
Without supplying the range, and have it delete everything for me.
An understandable request indeed; I can imagine advanced operations like these might get added over time by the AWS team (they...
Difference between Hive internal tables and external tables?
Can anyone tell me the difference between Hive's external table and internal tables.
I know the difference comes when dropping the table. I don't understand what you mean by the data and metadata is deleted in internal and only metadata is deleted in external tables.
Can anyone explain me in terms o...
Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '=
...ers.productID = rProductID;
END
Option 4: alter the field itself:
ALTER TABLE users CHARACTER SET utf8 COLLATE utf8_general_ci;
Unless you need to sort data in Unicode order, I would suggest altering all your tables to use utf8_general_ci collation, as it requires no code changes, and will spee...
Copy/duplicate database without using mysqldump
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You can duplicate a table without data by running:
CREATE TABLE x LIKE y;
(See the MySQL CREATE TABLE Docs)
You could write a script that takes the output from SHOW TABLES from one database and copies the schema to another. You should be abl...
Can I add a UNIQUE constraint to a PostgreSQL table, after it's already created?
I have the following table:
4 Answers
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