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Polymorphism in C++
...egorise them in various ways:
When is the polymorphic type-specific code selected?
Run time means the compiler must generate code for all the types the program might handle while running, and at run-time the correct code is selected (virtual dispatch)
Compile time means the choice of type-specif...
How do I delete from multiple tables using INNER JOIN in SQL server
...(you want to delete) to temporary table
INSERT INTO #DeleteIds(Id)
SELECT DISTINCT mt.MasterTableId
FROM MasterTable mt
INNER JOIN ...
WHERE ...
-- delete from first detail table using join syntax
DELETE d
FROM DetailTable_1 D
INNER JOIN #DeleteIds X
ON D.MasterTableId...
Count table rows
...
SELECT COUNT(*) FROM fooTable;
will count the number of rows in the table.
See the reference manual.
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Are nested transactions allowed in MySQL?
...Y) ENGINE=InnoDB;
START TRANSACTION;
INSERT
INTO t_test
VALUES (1);
SELECT *
FROM t_test;
id
---
1
SAVEPOINT tran2;
INSERT
INTO t_test
VALUES (2);
SELECT *
FROM t_test;
id
---
1
2
ROLLBACK TO tran2;
SELECT *
FROM t_test;
id
---
1
ROLLBACK;
SELECT *
FROM ...
How to find all tables that have foreign keys that reference particular table.column and have values
...
Here you go:
USE information_schema;
SELECT *
FROM
KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_NAME = 'X'
AND REFERENCED_COLUMN_NAME = 'X_id';
If you have multiple databases with similar tables/column names you may also wish to limit your query to a particul...
Does the join order matter in SQL?
...t matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.
For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.
First, outer joins are not commutative, so a LEFT JOIN b is no...
Fragment onCreateView and onActivityCreated called twice
....getFragmentManager().findFragmentByTag(mTag);
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
if (mFragment == null) {
mFragment = Fragment.instantiate(mActivity, mClass.getName());
ft.replace(android.R.id.content, mFragment, mTag);
} ...
Android: Coloring part of a string using TextView.setText()?
...eSpan(android.graphics.Typeface.BOLD);
// Set the text color for first 4 characters
sb.setSpan(fcs, 0, 4, Spannable.SPAN_INCLUSIVE_INCLUSIVE);
// make them also bold
sb.setSpan(bss, 0, 4, Spannable.SPAN_INCLUSIVE_INCLUSIVE);
yourTextView.setText(sb);
...
Join vs. sub-query
...
@JinghuiNiu Customers who bought expensive items: select custid from cust join bought using (custid) where price > 500. If a customer bought multiple expensive items, you'll get double-ups. To fix this, select custid from cust where exists (select * from bought where cust...
How to use z-index in svg elements?
...
d3.selection.prototype.moveToFront = function() { return this.each(function() { this.parentNode.appendChild(this); }); }; And then you can say selection.moveToFront() via stackoverflow.com/questions/14167863/…
...