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Convert timestamp to date in MySQL query
I want to convert a timestamp in MySQL to a date.
10 Answers
10
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Add Foreign Key to existing table
...n "SET FOREIGN_KEY_CHECKS=0;" before running the ADD CONSTRAINT command or SQL would complain "Cannot add or update a child row: a foreign key constraint fails".
– Erin Geyer
Mar 8 '17 at 13:03
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Modify table: How to change 'Allow Nulls' attribute from not null to allow null
How to change one attribute in a table using T-SQL to allow nulls (not null --> null)? Alter table maybe?
8 Answers
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NHibernate.MappingException: No persister for: XYZ
...guration..
If you're using app.config...
.
.
<property name="show_sql">true</property>
<property name="query.substitutions">true 1, false 0, yes 'Y', no 'N'</property>
<mapping assembly="Project.DomainModel"/> <!-- Here -->
</session-factory>
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Give examples of functions which demonstrate covariance and contravariance in the cases of both over
...mparator<java.util.Date> { ... } and you want to sort a List<java.sql.Date> with that comparator (java.sql.Date is a sub-class of java.util.Date), you can do with:
<T> void sort(List<T> what, Comparator<? super T> how)
but not with
<T> void sort(List<T>...
SQLite in Android How to update a specific row
...the line should be: myDB.update(TableName, cv, "_id=?", new String[]{id}). SQLite will automatically fill the fourth param into the "?" in the third param, i.e. the WHERE clause. If your third param contains n "?"s , the fourth param should be a String[] of length n
– Cristiano...
How to 'bulk update' with Django?
I'd like to update a table with Django - something like this in raw SQL:
5 Answers
5
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Select data from date range between two dates
...ously, second way is much more simple (only two cases against four).
Your SQL will look like:
SELECT * FROM Product_sales
WHERE NOT (From_date > @RangeTill OR To_date < @RangeFrom)
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Deleting all records in a database table
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If you are looking for a way to it without SQL you should be able to use delete_all.
Post.delete_all
or with a criteria
Post.delete_all "person_id = 5 AND (category = 'Something' OR category = 'Else')"
See here for more information.
The records are deleted wit...
What's the best way of structuring data on firebase?
...There is now a doc on structuring data. Also, see this excellent post on NoSQL data structures.
The main issue with hierarchical data, as opposed to RDBMS, is that it's tempting to nest data because we can. Generally, you want to normalize data to some extent (just as you would do with SQL) despite...