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Rails DB Migration - How To Drop a Table?
I added a table that I thought I was going to need, but now no longer plan on using it. How should I remove that table?
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Best way to check if a Data Table has a null value in it
what is the best way to check if a Data Table has a null value in it ?
6 Answers
6
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How to rename items in values() in Django?
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-1 because .values(supports__through_tables) and this hack doesn't (incidentally probably the most obvious use case for wanting to rename the ValuesQuerySet dict keys)
– wim
Aug 21 '14 at 13:12
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Looping through a hash, or using an array in PowerShell
I'm using this (simplified) chunk of code to extract a set of tables from SQL Server with BCP .
7 Answers
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What's the difference between TRUNCATE and DELETE in SQL
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General Overview
If you want to quickly delete all of the rows from a table, and you're really sure that you want to do it, and you do not have foreign keys against the tables, then a TRUNCATE is probably going to be faster than a DELETE.
Various system-specific issues have to be considered, a...
SQLite - UPSERT *not* INSERT or REPLACE
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Assuming three columns in the table: ID, NAME, ROLE
BAD: This will insert or replace all columns with new values for ID=1:
INSERT OR REPLACE INTO Employee (id, name, role)
VALUES (1, 'John Foo', 'CEO');
BAD: This will insert or replace 2 of the...
How to check if running in Cygwin, Mac or Linux?
...If you are doing that, it's your responsibility to ensure the correct executables (i.e., the CygWin ones) are being called, possibly by modifying the path beforehand or fully specifying the executable locations (e.g., /c/cygwin/bin/uname).
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Compile time string hashing
... GCC and not MSVC nor Intel compiler.
Here is the code snippet:
// CRC32 Table (zlib polynomial)
static constexpr uint32_t crc_table[256] = {
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
0xe0d5e91eL, 0...
SQL - Update multiple records in one query
I have table - config .
Schema:
config_name | config_value
9 Answers
9
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How to delete a row by reference in data.table?
My question is related to assignment by reference versus copying in data.table . I want to know if one can delete rows by reference, similar to
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