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Checking oracle sid and database name
...ght be worth noting that not all of the methods give you the same output:
SQL> select sys_context('userenv','db_name') from dual;
SYS_CONTEXT('USERENV','DB_NAME')
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orcl
SQL> select ora_database_name from dual;
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How to select rows that have current day's timestamp?
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See the difference: SQL-Fiddle Notice the FILTERED = 25 in the 2nd query.
– ypercubeᵀᴹ
Feb 8 '13 at 12:28
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mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to
I am trying to select data from a MySQL table, but I get one of the following error messages:
31 Answers
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Unknown Column In Where Clause
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SQL is evaluated backwards, from right to left. So the where clause is parsed and evaluate prior to the select clause. Because of this the aliasing of u_name to user_name has not yet occurred.
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Converting an array of objects to ActiveRecord::Relation
...rray to an ActiveRecord::Relation since a Relation is just a builder for a SQL query and its methods do not operate on actual data.
However, if what you want is a relation then:
for ActiveRecord 3.x, don’t call all and instead call scoped, which will give back a Relation which represents the sa...
NOT IN vs NOT EXISTS
...duce the row count to zero makes cardinality estimation very difficult. If SQL Server assumes that this will happen but in fact there were no NULL rows in the data the rest of the execution plan may be catastrophically worse, if this is just part of a larger query, with inappropriate nested loops ca...
How to truncate a foreign key constrained table?
...in PHPMYADMIN, this works only if you use all the transactions in the same SQL window (separated by a ;). This is because each fresh web SQL call will reset the FOREIGN_KEY_CHECKS to 1.
– Sablefoste
Oct 7 '13 at 21:17
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Oracle “(+)” Operator
I am checking some old SQL Statements for the purpose of documenting them and probably enhancing them.
4 Answers
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Relational Database Design Patterns? [closed]
...u want use in the future another DBMS? If yes then does not use to special SQL stuff of the current DBMS. Remove logic in your application.
Does not use:
white spaces in table names and column names
Non Ascii characters in table and column names
binding to a specific lower case or upper case. An...
Are PostgreSQL column names case-sensitive?
...olumn names) that are not double-quoted are folded to lower case in PostgreSQL. Column names that were created with double-quotes and thereby retained upper-case letters (and/or other syntax violations) have to be double-quoted for the rest of their life: ("first_Name")
So, yes, PostgreSQL column n...