大约有 47,000 项符合查询结果(耗时:0.0337秒) [XML]

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Get records with max value for each group of grouped SQL results

... There's a super-simple way to do this in mysql: select * from (select * from mytable order by `Group`, age desc, Person) x group by `Group` This works because in mysql you're allowed to not aggregate non-group-by columns, in which case mysql just returns the first row. T...
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Join vs. sub-query

... @JinghuiNiu Customers who bought expensive items: select custid from cust join bought using (custid) where price > 500. If a customer bought multiple expensive items, you'll get double-ups. To fix this, select custid from cust where exists (select * from bought where cust...
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How can I remove the gloss on a select element in Safari on Mac?

On Macs and iOS devices, in Safari, a <select> element with a background color generates a gloss over itself. This does not seem to happen in other operating systems. ...
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How to “add existing frameworks” in Xcode 4?

... As per Apple's documentation: In the project navigator, select your project. Select your target. Select the "Build Phases" tab. Open "Link Binaries With Libraries" expander. Click the + button. Select your framework. (optional) Drag and drop the added framework to the "Framework...
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Rename package in Android Studio

...n: In your Project pane, click on the little gear icon ( ) Uncheck / De-select the Compact Empty Middle Packages option Your package directory will now be broken up in individual directories Individually select each directory you want to rename, and: Right-click it Select Refactor Click o...
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How to do this in Laravel, subquery where in

...sider this code: Products::whereIn('id', function($query){ $query->select('paper_type_id') ->from(with(new ProductCategory)->getTable()) ->whereIn('category_id', ['223', '15']) ->where('active', 1); })->get(); ...
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Adding 'serial' to existing column in Postgres

...int, b text); CREATE TABLE bar (a serial, b text); INSERT INTO foo (a, b) SELECT i, 'foo ' || i::text FROM generate_series(1, 5) i; INSERT INTO bar (b) SELECT 'bar ' || i::text FROM generate_series(1, 5) i; -- blocks of commands to turn foo into bar CREATE SEQUENCE foo_a_seq; ALTER TABLE foo ALTER...
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SQL injection that gets around mysql_real_escape_string()

...ollowing query: $iId = mysql_real_escape_string("1 OR 1=1"); $sSql = "SELECT * FROM table WHERE id = $iId"; mysql_real_escape_string() will not protect you against this. The fact that you use single quotes (' ') around your variables inside your query is what protects you against this. The fo...
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How to check if a table exists in a given schema

... whether a table (or view) exists, and the current user has access to it? SELECT EXISTS ( SELECT FROM information_schema.tables WHERE table_schema = 'schema_name' AND table_name = 'table_name' ); The information schema is mainly useful to stay portable across major versions and...
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FIND_IN_SET() vs IN()

... SELECT name FROM orders,company WHERE orderID = 1 AND companyID IN (attachedCompanyIDs) attachedCompanyIDs is a scalar value which is cast into INT (type of companyID). The cast only returns numbers up to the...