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String literals and escape characters in postgresql
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Note that on PostgreSQL 9.0 E'testing\\x20double-slash' will evaluate as 'testing\\x20double-slash', so only single-slash approach works for E'string' style literals
– Alexander
Aug 14 '12 at 14:02
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Large, persistent DataFrame in pandas
...ad chunks of the CSV files in a for-loop approach and add them e.g., to an SQLite database step by step:
import pandas as pd
import sqlite3
from pandas.io import sql
import subprocess
# In and output file paths
in_csv = '../data/my_large.csv'
out_sqlite = '../data/my.sqlite'
table_name = 'my_tabl...
Real life example, when to use OUTER / CROSS APPLY in SQL
... processing the whole table COULD be true it would surprise me (i know the sql optimizer/compiler can disappoint from time to time but this would be crazy behaviour)
– Lee Tickett
Feb 15 '12 at 9:51
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On Duplicate Key Update same as insert
...ID; you need to specify the backend app you're using for the same.
For LuaSQL, a conn:getlastautoid() fetches the value.
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How can I copy data from one column to another in the same table?
...sible to copy data from column A to column B for all records in a table in SQL?
3 Answers
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Transactions in .net
...n transactions and ambient transactions. A connection transaction (such as SqlTransaction) is tied directly to the db connection (such as SqlConnection), which means that you have to keep passing the connection around - OK in some cases, but doesn't allow "create/use/release" usage, and doesn't allo...
Django: How to completely uninstall a Django app?
...o < 1.7 has a handy management command that will give you the necessary SQL to drop all the tables for an app. See the sqlclear docs for more information. Basically, running ./manage.py sqlclear my_app_name gets you get the SQL statements that should be executed to get rid of all traces of the ap...
SQL query return data from multiple tables
...roduce them if your database doesn't support them) - this is a function of SQL-Server (see info) and part of the reason I wrote this whole thing in the first place.
Part 2
Subqueries - what they are, where they can be used and what to watch out for
Cartesian joins AKA - Oh, the misery!
There a...
What is declarative programming? [closed]
... figure out the how.
Examples of declarative programming languages are SQL and Prolog.
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edited Aug 28 '16 at 9:19
Aquarius_...
PDO MySQL: Use PDO::ATTR_EMULATE_PREPARES or not?
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To answer your concerns:
MySQL >= 5.1.17 (or >= 5.1.21 for the PREPARE and EXECUTE statements) can use prepared statements in the query cache. So your version of MySQL+PHP can use prepared statements with the query cache. However, make careful no...