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MySQL: Insert record if not exists in table
...oDB;
Insert a record:
INSERT INTO table_listnames (name, address, tele)
SELECT * FROM (SELECT 'Rupert', 'Somewhere', '022') AS tmp
WHERE NOT EXISTS (
SELECT name FROM table_listnames WHERE name = 'Rupert'
) LIMIT 1;
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0
...
DISTINCT for only one column
...
If you are using SQL Server 2005 or above use this:
SELECT *
FROM (
SELECT ID,
Email,
ProductName,
ProductModel,
ROW_NUMBER() OVER(PARTITION BY Email ORDER BY ...
How can I use grep to find a word inside a folder?
...number in the file
'yourString*' String for search, followed by a wildcard character
-r Recursively search subdirectories listed
. Directory for search (current directory)
grep -nr 'MobileAppSer*' . (Would find MobileAppServlet.java or MobileAppServlet.class or MobileAppSer...
Easiest way to split a string on newlines in .NET?
...t your string pretty easily, like so:
aString.Split(Environment.NewLine.ToCharArray());
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Use 'class' or 'typename' for template parameters? [duplicate]
...s expected T will always be a class, with "typename" if other types (int, char* whatever) may be expected. Consider it a usage hint.
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How to set selected value of jquery select2?
This belong to codes prior to select2 version 4
28 Answers
28
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Fast way to discover the row count of a table in PostgreSQL
...in your case.
Instead of getting the exact count (slow with big tables):
SELECT count(*) AS exact_count FROM myschema.mytable;
You get a close estimate like this (extremely fast):
SELECT reltuples::bigint AS estimate FROM pg_class where relname='mytable';
How close the estimate is depends on ...
Declaring an unsigned int in Java
...
Use char for 16 bit unsigned integers.
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Replace one substring for another string in shell script
...easily breaks on any nontrivial input string (irregular spacing, shell metacharacters, etc).
– tripleee
Jul 17 '18 at 16:54
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How to insert a newline in front of a pattern?
...adability - the only caveat is that you then need to double all literal \ chars.
– mklement0
Nov 30 '15 at 3:59
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