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Does MySQL ignore null values on unique constraints?
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Yes, MySQL allows multiple NULLs in a column with a unique constraint.
CREATE TABLE table1 (x INT NULL UNIQUE);
INSERT table1 VALUES (1);
INSERT table1 VALUES (1); -- Duplicate entry '1' for key 'x'
INSERT table1 VALUES (NULL);...
SQL Server: SELECT only the rows with MAX(DATE)
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For MySql you can do something like the following:
select OrderNO, PartCode, Quantity from table a
join (select ID, MAX(DateEntered) from table group by OrderNO) b on a.ID = b.ID
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How do I check if a column is empty or null in MySQL?
...OR some_col = ' ' (one space inserted in the string) then it works on both MySQL and Oracle, see answer of "onedaywhen". some_col = '' doesn't work on Oracle as empty strings mean NULL there.
– Johanna
May 18 '15 at 14:07
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How do I show the schema of a table in a MySQL database?
From the MySQL console, what command displays the schema of any given table?
5 Answers
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How to delete from multiple tables in MySQL?
...h out to an EXISTS in 99% of the cases and then there is the 1% where this MySQL syntax takes the day.
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How to refer to relative paths of resources when working with a code repository
.... How do you solve it when you have the following tree structure: /Project_Root_dir /python_files_dir /Some more subdirs here py_file.py /resources /some subdirs here resource_file.csv
– olamundo
Aug 14 '09 at 12...
Reading an Excel file in PHP [closed]
... you want to use the data in the excel file. If you want to import it into mysql, you could simply save it as a CSV formatted file and then use fgetcsv to parse it.
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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...
What's the difference between VARCHAR and CHAR?
What's the difference between VARCHAR and CHAR in MySQL?
14 Answers
14
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Best way to make Django's login_required the default
... Simply check each view function.
import os
import re
def view_modules( root ):
for path, dirs, files in os.walk( root ):
for d in dirs[:]:
if d.startswith("."):
dirs.remove(d)
for f in files:
name, ext = os.path.splitext(f)
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