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Rails DB Migration - How To Drop a Table?
I added a table that I thought I was going to need, but now no longer plan on using it. How should I remove that table?
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How do I cast a string to integer and have 0 in case of error in the cast with PostgreSQL?
In PostgreSQL I have a table with a varchar column. The data is supposed to be integers and I need it in integer type in a query. Some values are empty strings.
The following:
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How to create a table from select query result in SQL Server 2008 [duplicate]
I want to create a table from select query result in SQL Server, I tried
6 Answers
6
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How do I quickly rename a MySQL database (change schema name)?
...e following seems to work: create the new empty database, then rename each table in turn into the new database:
RENAME TABLE old_db.table TO new_db.table;
You will need to adjust the permissions after that.
For scripting in a shell, you can use either of the following:
mysql -u username -ppassw...
MySQL “WITH” clause
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Update: MySQL 8.0 is finally getting the feature of common table expressions, including recursive CTEs.
Here's a blog announcing it: http://mysqlserverteam.com/mysql-8-0-labs-recursive-common-table-expressions-in-mysql-ctes/
Below is my earlier answer, which I originally wrote in 200...
Read specific columns from a csv file with csv module?
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I think Pandas is a perfectly acceptable solution. I use Pandas often and really like the library, but this question specifically referenced the CSV module.
– frankV
May 23 '17 at 17:05
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COUNT DISTINCT with CONDITIONS
...tinct items in a column subject to a certain condition, for example if the table is like this:
5 Answers
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SQL variable to hold list of integers
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Table variable
declare @listOfIDs table (id int);
insert @listOfIDs(id) values(1),(2),(3);
select *
from TabA
where TabA.ID in (select id from @listOfIDs)
or
declare @listOfIDs varchar(1000);
SET @listOfIDs = ',1,2,3...
How to change collation of database, table, column?
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You need to either convert each table individually:
ALTER TABLE mytable CONVERT TO CHARACTER SET utf8mb4
(this will convert the columns just as well), or export the database with latin1 and import it back with utf8mb4.
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What are DDL and DML?
... the database.
CREATE – to create database and its objects like (table, index, views, store procedure, function and triggers)
ALTER – alters the structure of the existing database
DROP – delete objects from the database
TRUNCATE – remove all records from a table, including all ...