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Oracle: how to UPSERT (update or insert into a table?)
...before the insert regardless of how many concurrent calls are made to same SQL code. Worst case, you may get lots of contention and Oracle will take much longer to reach a final state.
– Neo
Nov 6 '12 at 13:23
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Is there any boolean type in Oracle databases?
... any Boolean type in Oracle databases, similar to the BIT datatype in Ms SQL Server?
11 Answers
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How to split a string literal across multiple lines in C / Objective-C?
I have a pretty long sqlite query:
9 Answers
9
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Postgis installation: type “geometry” does not exist
...eate table with Postgis. I do it by this page . But when I import postgis.sql file, I get a lot of errors:
10 Answers
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What is causing this ActiveRecord::ReadOnlyRecord error?
... you use this option, saving the same
record will now fail. Use find_by_sql
to work around.
Using find_by_sql is not really an alternative as it returns raw row/column data, not ActiveRecords. You have two options:
Force the instance variable @readonly to false in the record (hack)
Use :in...
Postgres: INSERT if does not exist already
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@TusharJain prior to PostgreSQL 9.5 you can do an "old fashioned" UPSERT (with CTE) but you may experience problems with race conditions and it will not be performant as 9.5 style. There is a good detail about upsert on this blog (in the updated area at...
Foreign key constraint may cause cycles or multiple cascade paths?
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SQL Server does simple counting of cascade paths and, rather than trying to work out whether any cycles actually exist, it assumes the worst and refuses to create the referential actions (CASCADE): you can and should still cr...
MySQL: selecting rows where a column is null
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SQL NULL's special, and you have to do WHERE field IS NULL, as NULL cannot be equal to anything,
including itself (ie: NULL = NULL is always false).
See Rule 3 https://en.wikipedia.org/wiki/Codd%27s_12_rules
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MySQL ON vs USING?
In a MySQL JOIN , what is the difference between ON and USING() ? As far as I can tell, USING() is just more convenient syntax, whereas ON allows a little more flexibility when the column names are not identical. However, that difference is so minor, you'd think they'd just do away with USI...
How to escape apostrophe (') in MySql?
The MySQL documentation says that it should be \' . However, both scite and mysql shows that '' works. I saw that and it works. What should I do?
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