大约有 41,000 项符合查询结果（耗时：0.0394秒） [XML]
WHERE vs HAVING
Why do you need to place columns you create yourself (for example select 1 as "number" ) after HAVING and not WHERE in MySQL?
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Getting the minimum of two values in SQL
...led OwedPast . They are both results of some subqueries in SQL. How can I select the smaller of the two and return it as a value titled PaidForPast ?
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Unioning two tables with different number of columns
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Add extra columns as null for the table having less columns like
Select Col1, Col2, Col3, Col4, Col5 from Table1
Union
Select Col1, Col2, Col3, Null as Col4, Null as Col5 from Table2
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How to disable/enable select field using jQuery?
...gt;
<label for="pizza">I would like to order a</label>
<select id="pizza_kind" name="pizza_kind">
<option>(choose one)</option>
<option value="margaritha">Margaritha</option>
<option value="hawai">Hawai</option>
</select>
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How do I change selected value of select2 dropdown with JqGrid?
I'm using Oleg's select2 demo , but I am wondering whether it would be possible to change the currently selected value in the dropdown menu.
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How to request a random row in SQL?
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See this post: SQL to Select a random row from a database table. It goes through methods for doing this in MySQL, PostgreSQL, Microsoft SQL Server, IBM DB2 and Oracle (the following is copied from that link):
Select a random row with MySQL:
SELE...
DISTINCT for only one column
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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 ...
Displaying better error message than “No JSON object could be decoded”
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simplejson.decoder.JSONDecodeError: Expecting object: line 1 column 5 (char 5)
Much better! Likewise for other common errors like capitalizing True.
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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 ...
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
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