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How to find Unused Amazon EC2 Security groups
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If you select all of your security groups in the EC2 console, then press actions -> Delete Security Groups, a popup will appear telling you that you cannot delete security groups that are attached to instances, other security gro...
SQL: deleting tables with prefix
...r you:
In the MySQL shell or through PHPMyAdmin, use the following query
SELECT CONCAT( 'DROP TABLE ', GROUP_CONCAT(table_name) , ';' )
AS statement FROM information_schema.tables
WHERE table_name LIKE 'myprefix_%';
This will generate a DROP statement which you can than copy and execut...
In MySQL, can I copy one row to insert into the same table?
...e) but I want to do this without having to list all the columns after the "select", because this table has too many columns.
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What is the benefit of zerofill in MySQL?
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When you select a column with type ZEROFILL it pads the displayed value of the field with zeros up to the display width specified in the column definition. Values longer than the display width are not truncated. Note that usage of ZER...
Check if a class has a member function of a given signature
...her down
Check for member x in a given class. Could be var, func, class, union, or enum:
CREATE_MEMBER_CHECK(x);
bool has_x = has_member_x<class_to_check_for_x>::value;
Check for member function void x():
//Func signature MUST have T as template variable here... simpler this way :\
CREAT...
Troubleshooting “Illegal mix of collations” error in mysql
Am getting the below error when trying to do a select through a stored procedure in MySQL.
16 Answers
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MySQL: How to copy rows, but change a few fields?
...able
( Event_ID
, col2
...
)
SELECT "155"
, col2
...
FROM Table WHERE Event_ID = "120"
Here, the col2, ... represent the remaining columns (the ones other than Event_ID) in your table.
...
How to do a regular expression replace in MySQL?
...ositions and perform substring substitution and extraction, respectively.
SELECT REGEXP_REPLACE('Stackoverflow','[A-Zf]','-',1,0,'c');
-- Output:
-tackover-low
DBFiddle Demo
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MySQL INSERT INTO table VALUES.. vs INSERT INTO table SET
...statement insert rows based on explicitly specified values. The INSERT ... SELECT form inserts rows selected from another table or tables.
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MySQL indexes - what are the best practices?
...t them. Generally I put an index on any fields that I will be searching or selecting using a WHERE clause but sometimes it doesn't seem so black and white.
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