You can look in sys.types or use TYPE_ID: IF TYPE_ID(N’MyType’) IS NULL … Just a precaution: using type_id won’t verify that the type is a table type–just that a type by that name exists. Otherwise gbn’s query is probably better.
Counting rows in big tables is known to be slow in PostgreSQL. The MVCC model requires a full count of live rows for a precise number. There are workarounds to speed this up dramatically if the count does not have to be exact like it seems to be in your case. (Remember that even an … Read more
create table my_table ( column_a integer not null, column_b integer not null, column_c varchar(50), primary key (column_a, column_b) );
The following query gives names of all sequences. SELECT c.relname FROM pg_class c WHERE c.relkind = ‘S’; Typically a sequence is named as ${table}_id_seq. Simple regex pattern matching will give you the table name. To get last value of a sequence use the following query: SELECT last_value FROM test_id_seq;
mysql -u <user> -p -e ‘select * from schema.table’ (Note the use of single quotes rather than double quotes, to avoid the shell expanding the * into filenames)
Take a look at this. Change your query to: SET @rank=0; SELECT @rank:=@rank+1 AS rank, itemID, COUNT(*) as ordercount FROM orders GROUP BY itemID ORDER BY ordercount DESC; SELECT @rank; The last select is your count.
EXISTS (or NOT EXISTS) is specially designed for checking if something exists and therefore should be (and is) the best option. It will halt on the first row that matches so it does not require a TOP clause and it does not actually select any data so there is no overhead in size of columns. … Read more
Use the queryset object update method: MyModel.objects.filter(pk=some_value).update(field1=’some value’)
Without any further information, which Database etc the best we can do is something like Sql Server SELECT TOP 1 * FROM Table ORDER BY ID DESC MySql SELECT * FROM Table ORDER BY ID DESC LIMIT 1
jsonb in Postgres 9.4+ You can use the same query as below, just with jsonb_array_elements(). But rather use the jsonb “contains” operator @> in combination with a matching GIN index on the expression data->’objects’: CREATE INDEX reports_data_gin_idx ON reports USING gin ((data->’objects’) jsonb_path_ops); SELECT * FROM reports WHERE data->’objects’ @> ‘[{“src”:”foo.png”}]’; Since the key objects … Read more