大约有 9,000 项符合查询结果（耗时：0.0229秒） [XML]
Why does this async action hang?
... string connectionString = dataSource.ConnectionString;
// Start the SQL and pass back to the caller until finished
return Task.Run(
() =>
{
// Copy the SQL connection so that we don't get two commands running at the same time on the same open connection
...
How to include “zero” / “0” results in COUNT aggregate?
I've just got myself a little bit stuck with some SQL. I don't think I can phrase the question brilliantly - so let me show you.
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How to do an INNER JOIN on multiple columns
...he above solution and go the following error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'INNER_JOIN airports to_port ON (to_port.code = flights.tairport) WHERE ' at line 7
– Kir...
Export from sqlite to csv using shell script
I'm making a shell script to export a sqlite query to a csv file, just like this:
5 Answers
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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 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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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...