大约有 9,000 项符合查询结果（耗时：0.0378秒） [XML]
What is Scala's yield?
...ndrum - Which interestingly enough is the same order in which the original SQL spec outlines. Somewhere along the way the SQL language inverted the order, but it makes complete sense to first describe what you are pulling from followed by what you expect to get out of it.
– Jo...
Get generated id after insert
I'm using the SQLite with Android, and I want to know the best way to get the generated id of the row I inserted.
5 Answers...
How big is too big for a PostgreSQL table?
...,1 as c2,2 as c3
from generate_series(1,90000000) x;
https://wiki.postgresql.org/wiki/FAQ
Limit Value
Maximum Database Size Unlimited
Maximum Table Size 32 TB
Maximum Row Size 1.6 TB
Maximum Field Size 1 GB
Maximum Rows per Table Unlimited
Maximum Columns...
Examples of GoF Design Patterns in Java's core libraries
...nd - TextComponent's Undo/Redo.
Interpreter - RegEx (java.util.regex.) and SQL (java.sql.) API.
Prototype - Not 100% sure if this count, but I thinkg clone() method can be used for this purpose.
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快速理解 高频对冲套利自动交易（程式化交易） - 更多技术 - 清泛网 - 专注...
...言，我才实盘测试交易15个交易日，我也不知道每月收益如何。按照估算，20万的实盘账户，每月稳定有净利润5000元以上（即，年收益大约30%以上，权益回撤不超过10%），同时，产生的手续费比净利润略低些，大约是净利润的9成...
What is causing ERROR: there is no unique constraint matching given keys for referenced table?
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In postgresql all foreign keys must reference a unique key in the parent table, so in your bar table you must have a unique (name) index.
See also http://www.postgresql.org/docs/9.1/static/ddl-constraints.html#DDL-CONSTRAINTS-FK and s...
How to add a line break in C# .NET documentation
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/// <summary>
/// <para>Get a human-readable variant of the SQL WHERE statement of the search element.</para>
/// Rather than return SQL, this method returns a string with icon-tokens, which
/// could be used to represent the search in a condensed pictogram format.
/// </sum...
PHP function to build query string from array
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Implode will combine an array into a string for you, but to make an SQL query out a kay/value pair you'll have to write your own function.
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Hibernate Annotations - Which is better, field or property access?
...a is to shy away from ORM solutions altogether. Learn how to write proper SQL.
– duffymo
May 27 '16 at 16:44
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JPA EntityManager: Why use persist() over merge()?
...ached, entityToSave);
return attached;
}
Although if connected to MySQL merge() could be as efficient as persist() using a call to INSERT with ON DUPLICATE KEY UPDATE option, JPA is a very high level programming and you can't assume this is going to be the case everywhere.
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