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What is the difference between declarative and imperative programming? [closed]
...you want; you are only saying what you want. You could say the same about SQL.
One benefit of declarative programming is that it allows the compiler to make decisions that might result in better code than what you might make by hand. Running with the SQL example, if you had a query like
SELECT ...
How to create a MySQL hierarchical recursive query
I have a MySQL table which is as follows:
15 Answers
15
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How can I get a list of all functions stored in the database of a particular schema in PostgreSQL?
I want to be able to connect to a PostgreSQL database and find all of the functions for a particular schema.
9 Answers
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select * vs select column
...e for everything (including table data) is based on defined I/O Pages (in SQL Server for e.g., each Page is 8 kilobytes). And every I/O read or write is by Page.. I.e., every write or read is a complete Page of data.
Because of this underlying structural constraint, a consequence is that Each row...
How do I quickly rename a MySQL database (change schema name)?
The MySQL manual at MySQL covers this.
48 Answers
48
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how to exclude null values in array_agg like in string_agg using postgres?
...
SQL Fiddle
select
id,
(select array_agg(a) from unnest(canonical_users) a where a is not null) canonical_users,
(select array_agg(a) from unnest(non_canonical_users) a where a is not null) non_canonical_users
fro...
How do you return the column names of a table?
How would I return the column names of a table using SQL Server 2008? i.e. a table contains these columns- id, name, address, country and I want to return these as data.
...
Cast int to varchar
...m t9;
select CONVERT(id, CHAR(50)) as colI1
from t9;
See the following SQL — in action — over at SQL Fiddle:
/*! Build Schema */
create table t9 (id INT, name VARCHAR(55));
insert into t9 (id, name) values (2, 'bob');
/*! SQL Queries */
select CAST(id as CHAR(50)) as col1 from t9;
select C...
How can I drop all the tables in a PostgreSQL database?
How can I drop all tables in PostgreSQL, working from the command line?
24 Answers
24
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updating table rows in postgres using subquery
...FROM (SELECT address_id, customer, address, partn
FROM /* big hairy SQL */ ...) AS subquery
WHERE dummy.address_id=subquery.address_id;
This syntax is not standard SQL, but it is much more convenient for this type of query than standard SQL. I believe Oracle (at least) accepts something sim...