大约有 47,000 项符合查询结果(耗时:0.0368秒) [XML]

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Remove duplicate rows in MySQL

...ate temporary table tmpTable (id int); insert into tmpTable (id) select id from YourTable yt where exists ( select * from YourTabe yt2 where yt2.title = yt.title and yt2.company = yt.company and yt2.site_id = yt.si...
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MySQL/SQL: Group by date only on a Datetime column

... Cast the datetime to a date, then GROUP BY using this syntax: SELECT SUM(foo), DATE(mydate) FROM a_table GROUP BY DATE(a_table.mydate); Or you can GROUP BY the alias as @orlandu63 suggested: SELECT SUM(foo), DATE(mydate) DateOnly FROM a_table GROUP BY DateOnly; Though I don't think...
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How do I see what character set a MySQL database / table / column is?

... Here's how I'd do it - For Schemas (or Databases - they are synonyms): SELECT default_character_set_name FROM information_schema.SCHEMATA WHERE schema_name = "schemaname"; For Tables: SELECT CCSA.character_set_name FROM information_schema.`TABLES` T, information_schema.`COLLATION_CHAR...
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Is there any performance gain in indexing a boolean field?

... It depends on the actual queries and the selectivity of the index/query combination. Case A: condition WHERE isok = 1 and nothing else there: SELECT * FROM tableX WHERE isok = 1 If the index is selective enough (say you have 1M rows and only 1k have isok = 1), ...
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How do I map lists of nested objects with Dapper

... probably work: Grab the courses: var courses = cnn.Query<Course>("select * from Courses where Category = 1 Order by CreationDate"); Grab the relevant mapping: var mappings = cnn.Query<CourseLocation>( "select * from CourseLocations where CourseId in @Ids", new {Ids = course...
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SQL how to make null values come last when sorting ascending

... select MyDate from MyTable order by case when MyDate is null then 1 else 0 end, MyDate share | improve this answer ...
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java.sql.SQLException: - ORA-01000: maximum open cursors exceeded

... a query, specifically the position where a reader is in a ResultSet. Each SELECT statement has a cursor, and PL/SQL stored procedures can open and use as many cursors as they require. You can find out more about cursors on Orafaq. A database instance typically serves several different schemas, man...
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How to change package name of an Android Application

... Right-click on the package name (src/com.android.gesture.builder). Select Refactor > Rename and change the name, for example to com.android.gestureNEW.builder. Open the manifest file. Inside the <manifest> tag, change the package name to com.android.gestureNEW.builder. ...
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PHP MySQL Google Chart JSON - Complete Example

... else { //echo ("Connect Successfully"); } $query = "SELECT Date_time, Tempout FROM alarm_value"; // select column $aresult = $con->query($query); ?> <!DOCTYPE html> <html> <head> <title>Massive Electronics</title> <script ty...
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PostgreSQL: Modify OWNER on all tables simultaneously in PostgreSQL

...and sequences too. Here's what I did: Tables: for tbl in `psql -qAt -c "select tablename from pg_tables where schemaname = 'public';" YOUR_DB` ; do psql -c "alter table \"$tbl\" owner to NEW_OWNER" YOUR_DB ; done Sequences: for tbl in `psql -qAt -c "select sequence_name from information_schem...