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Can I have multiple primary keys in a single table?
...xed columns on the same table). Be sure to consult your specific flavor of SQL's manual for details on the exact language syntax used.
– 4AM
Jan 25 '18 at 17:16
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How to get last N records with activerecord?
... Try this with Postgres! I've certainly had trouble with first. In SQL the order isn't guaranteed unless you specify it, but MySQL is more forgiving.
– Ghoti
Jul 15 '12 at 10:56
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Storing money in a decimal column - what precision and scale?
...age. Accountants generally seem to favour four decimal places.
PS Avoid SQL Server's MONEY data type because it has serious issues with accuracy when rounding, among other considerations such as portability etc. See Aaron Bertrand's blog.
Microsoft and language designers chose banker's roundin...
A connection was successfully established with the server, but then an error occurred during the pre
...while some threads threw this exception, some other threw:
System.Data.SqlClient.SqlException (0x80131904): Connection Timeout Expired. The timeout period elapsed while attempting to consume the pre-login handshake acknowledgement. This could be because the pre-login handshake failed or the se...
How to speed up insertion performance in PostgreSQL
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See populate a database in the PostgreSQL manual, depesz's excellent-as-usual article on the topic, and this SO question.
(Note that this answer is about bulk-loading data into an existing DB or to create a new one. If you're interested DB restore performance wi...
Disabling contextual LOB creation as createClob() method threw error
...
Basically here we are simply checking
whether we can call the
java.sql.Connection methods for LOB
creation added in JDBC 4. We not only
check whether the java.sql.Connection
declares these methods, but also
whether the actual java.sql.Connection
instance implements them (i.e. can b...
Counting null and non-null values in a single query
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This works for Oracle and SQL Server (you might be able to get it to work on another RDBMS):
select sum(case when a is null then 1 else 0 end) count_nulls
, count(a) count_not_nulls
from us;
Or:
select count(*) - count(a), count(a) from us...
win7 安装项目管理工具redmine2.5.1 - 开源 & Github - 清泛网 - 专注C/C++及内核技术
...有的软件包发放在github上。如果有Linux服务器平台，建议使用Linux，安装原理差不多。
三、安装rails和redmine
1、安装railsinstaller
参考http://blog.csdn.net/wind520/article/details/19246887
如果没有特别的要求，一直安装即可。
2、安装i...
Only initializers, entity members, and entity navigation properties are supported
...
Entity is trying to convert your Paid property to SQL and can't because it's not part of the table schema.
What you can do is let Entity query the table with no Paid filter and then filter out the not Paid ones.
public ActionResult Index()
{
var debts = storeDB.Orders...
How to store arrays in MySQL?
I have two tables in MySQL. Table Person has the following columns:
7 Answers
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