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Delete sql rows where IDs do not have a match from another table
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Using LEFT JOIN/IS NULL:
DELETE b FROM BLOB b
LEFT JOIN FILES f ON f.id = b.fileid
WHERE f.id IS NULL
Using NOT EXISTS:
DELETE FROM BLOB
WHERE NOT EXISTS(SELECT NULL
FROM FILES f
WHERE f.id = fileid)
Using NOT IN:
DELETE FROM BLOB
WHERE fi...
MySQL Multiple Joins in one query?
... dashboard_data.headline, dashboard_data.message, dashboard_messages.image_id, images.filename
FROM dashboard_data
INNER JOIN dashboard_messages
ON dashboard_message_id = dashboard_messages.id
INNER JOIN images
ON dashboard_messages.image_id = images.image_id
However be ...
How do I drop a foreign key constraint only if it exists in sql server?
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The more simple solution is provided in Eric Isaacs's answer. However, it will find constraints on any table. If you want to target a foreign key constraint on a specific table, use this:
IF EXISTS (SELECT *
FROM sys.foreign_keys
WHERE object_id = O...
How to transfer some data to another Fragment?
...lass implements Serializable {
private static final long serialVersionUID = -2163051469151804394L;
private int id;
private String created;
}
In you FromFragment:
Bundle args = new Bundle();
args.putSerializable(TAG_MY_CLASS, myClass);
Fragment toFragment = new ToFragment();
toFragment...
Database design for audit logging
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One method that is used by a few wiki platforms is to separate the identifying data and the content you're auditing. It adds complexity, but you end up with an audit trail of complete records, not just listings of fields that were edited that you then have to mash up to give the user an ide...
How are the points in CSS specificity calculated
...earching specificity I stumbled upon this blog - http://www.htmldog.com/guides/cssadvanced/specificity/
7 Answers
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SQL SELECT speed int vs varchar
...your (say) 8-byte ints are longer than ascii varchars holding some textual IDs of avg length 3-4 chars. So, this answer - being imprecise and lacking any specific context or experimental results - doesn't really answer the question. Everyone knows that varchars are allowed to take much more space th...
SQLAlchemy: cascade delete
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The problem is that sqlalchemy considers Child as the parent, because that is where you defined your relationship (it doesn't care that you called it "Child" of course).
If you define the relationship on the Parent class instead, it will work:
children = rel...
Reset auto increment counter in postgres
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If you created the table product with an id column, then the sequence is not simply called product, but rather product_id_seq (that is, ${table}_${column}_seq).
This is the ALTER SEQUENCE command you need:
ALTER SEQUENCE product_id_seq RESTART WITH 1453
You can ...
Compare JavaScript Array of Objects to Get Min / Max
... This makes sense, I've been stuck with thinking about comparing data inside the array to each other instead of an external high/low number.
– firedrawndagger
Jan 14 '12 at 19:01
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