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What columns generally make good indexes?
...earching the results speedily from tables. So it is most important step to select which columns to be indexed. There are two major places where we can consider indexing: columns referenced in the WHERE clause and columns used in JOIN clauses. In short, such columns should be indexed against which yo...
How to do an update + join in PostgreSQL?
... coming from mysql it's unintuitive that the same join used for select won't also update just by adding a set phrase :( still - the syntax for this is probably easier for a newcomer to sql to master.
– WEBjuju
Jul 16 at 19:47
...
Strip Leading and Trailing Spaces From Java String
... answered Jul 11 '11 at 15:40
Richard HRichard H
32.9k3333 gold badges101101 silver badges130130 bronze badges
...
PostgreSQL query to list all table names?
...
What bout this query (based on the description from manual)?
SELECT table_name
FROM information_schema.tables
WHERE table_schema='public'
AND table_type='BASE TABLE';
share
|
im...
How to detect Ctrl+V, Ctrl+C using JavaScript?
... Dude! Thanks! This is exactly what I needed to enable users to select an "element" (calendar entry) in a web app I'm writing, hit ctrl + c to "copy" it, then ctrl+v to "paste" it, all without actually interacting with the allmighty blessed clipboard. ctrl+c I remember what they're clicke...
How to make a variadic macro (variable number of arguments)
...void)0) //strip out PRINT instructions from code
#endif
void print(const char *fmt, ...) {
va_list args;
va_start(args, fmt);
vsprintf(str, fmt, args);
va_end(args);
printf("%s\n", str);
}
int main() {
PRINT("[%s %d, %d] Hello World", "March", 26, 2009);
retur...
Maven error “Failure to transfer…”
...ed.properties).
Then go back into Eclipse, Right-click on the project and select Maven > Update Project. I selected to "Force Update of Snapshots/Releases". Click Ok and the dependencies finally resolved correctly.
shar...
Join between tables in two different databases?
...
Yes, assuming the account has appropriate permissions you can use:
SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
You just need to prefix the table reference with the name of the database it resides in.
...
Difference between a theta join, equijoin and natural join
...ed SQL query would be like this (you can play with all the examples here)
SELECT *
FROM Product
JOIN Component
ON Product.Pname = Component.Pname
and the result:
| PNAME | PRICE | CNAME | COST |
----------------------------------
| Laptop | 1500 | CPU | 500 |
| Laptop | 1500 | hdd ...
Comparing date ranges
... range_start, here's some simple SQL to retrieve all the matching rows:
SELECT *
FROM periods
WHERE NOT (range_start > @check_period_end
OR range_end < @check_period_start)
Note the NOT in there. Since the two simple rules finds all the non-matching rows, a simple NOT will reve...