Postgres source SQL for existing table - sql

I need to extract the source SQL for an existing table in postgres. Is it is possible?
Example: If I have a customertable, created in pgadmin, with 2 columns: id (integer), name (text). Is there way I can extract/get the CREATE function for this existing table, so I get a SQL with “CREATE TABLE customer ...” without having to write the whole SQL of the table in hand?

pgadmin (III,4):
right click on table name -> Scripts-> CREATE sript
psql:
pg_dump -s -t table_name

Related

Trigger to update table column when data is inserted in another table from a different database

I have a database table named vendor_invoice which contains columns invoiceNo and paymentref in database Interface. I want to update the paymentref column once data has been inserted into another database table named APTCR which is located in another database, JBDAT. Note that table APTCR has both the paymentref and invoiceno columns.
It would be possible if you use like oracle dblink or db2 federation or change data capture software.
If you use dblink or federation. You can use trigger :
create or replace trigger aaa
begin
...
end;
Otherwise, IBM IDR, Oracle Data Replication would be a good solution

How to copy table by spark-sql

Actually, I want to move one table to another database.
But spark don't permit this.
Then, how to copy table by spark-sql?
I already tried this.
SELECT *
INTO table1 IN new_database
FROM old_database.table1
But it was not working.
maybe try:
CREATE TABLE new_db.new_table AS
SELECT *
FROM old_db.old_table;
To preserve partitioning and storage format do the following-
Get the complete schema of the existing table by running-
show create table db.old_table
The above query will output the table schema which you can just execute after changing the path name and table name.
Then insert all the rows into the new blank table using-
insert into db.new_table select * from db.old_table
The following snippet will create a new table while preserving the definition of the "old" table.
CREATE TABLE db.new_table LIKE db.old_table;
For more info, check the doc's CREATE TABLE.

Dynamically creating tables using information held in another table

I want to create a table in sql using the columns details (name, data type etc.) stored in anther table in the database.
Depending on the database you can use the information schema tables. They hold the information you are looking for. Look for the table that describes the columns.
Postgres: http://www.postgresql.org/docs/8.4/interactive/information-schema.html
MySQL: http://dev.mysql.com/doc/refman/5.0/en/information-schema.html
You can query these tables and use 'select into' to insert the results into your other table.
One opinion is to create CREATE TABLE query and execute it in ADO.NET like shown here this
Try out this code
CREATE TABLE new_table
AS
SELECT *
FROM old_table
WHERE 1 = 2;

Create a replica of a sql table

I need a query to create a table which is the exact replica but with different table name and without any data from the source table using a sql query!
You can try this
SELECT * INTO Table_Copy
FROM Table
where 1=2
It will create a empty table with the same structure.
SQL Server Management Studio
Object Explorer
Connect -> Your server
Databases -> Choose Database
Tables
Right Click Your Table
Script Table as -> Create To -> New Query Editor Window
Jonathan has it (upvoted), and you should probably go with that because it's more portable. I normally use something similar:
SELECT TOP 0 * INTO [New_Table] FROM [Old_Table]
I think this better expresses what you're doing, but I like Jonathan's because 'TOP 0' is SQL Server specific, and so his is more portable.
For MySQL, you can call SHOW CREATE TABLE table_name;
It will display a CREATE TABLE query. Simply change the table name in that query and you're good to go.
http://dev.mysql.com/doc/refman/5.1/en/show-create-table.html
If you use Postgresql:
CREATE TABLE LIKE table_name
http://www.postgresql.org/docs/8.1/static/sql-createtable.html
SELECT * INTO Table_Copy
FROM Table
where 1=2
This worked very well, when i tried to create a replica of the table without any data's.
SELECT * INTO Table_Copy
FROM Table
This will create a replica with the data's too.
This can help you:
CREATE TABLE foo AS SELECT...
Read more here
select * into newtablename from sourcetablename
go
truncate newtablename
go
That will result in an exact copy but it also copies the data at first which you remove with the truncate statement.
create table <new table name> as select * from <old tale name from which you would like to extract data>
It will create a new table with a different name but will copy all existing data from the old table to new table.
in postgres you can use INHERITS or LIKE keyword to make replica of a table(only copies structure of the table)
CREATE TABLE client_new (LIKE client);
or
CREATE TABLE client_new () INHERITS (client)
Use of INHERITS creates a persistent relationship between the new child table and its parent table(s). Schema modifications to the parent(s) normally propagate to children as well, and by default the data of the child table is included in scans of the parent(s).
LIKE clause specifies a table from which the new table automatically copies all column names, their data types, and their not-null constraints.Unlike INHERITS, the new table and original table are completely decoupled after creation is complete. Changes to the original table will not be applied to the new table, and it is not possible to include data of the new table in scans of the original table.

SQL Command for copying table

What is the SQL command to copy a table from one database to another database?
I am using MySQL and I have two databases x and y. Suppose I have a table in x called a and I need to copy that table to y database.
Sorry if the question is too novice.
Thanks.
If the target table doesn't exist....
CREATE TABLE dest_table AS (SELECT * FROM source_table);
If the target table does exist
INSERT INTO dest_table (SELECT * FROM source_table);
Caveat: Only tested in Oracle
If your two database are separated, the simplest thing to do would be to create a dump of your table and to load it into the second database. Refer to your database manual to see how a dump can be performed.
Otherwise you can use the following syntax (for MySQL)
INSERT INTO database_b.table (SELECT * FROM database_a.table)
Since your scenario involves two different databases, the correct query should be...
INSERT INTO Y..dest_table (SELECT * FROM source_table);
Query assumes, you are running it using X database.
If you just want to copy the contents, you might be looking for select into:
http://www.w3schools.com/Sql/sql_select_into.asp. This will not create an identical copy though, it will just copy every row from one table to another.
At the command line
mysqldump somedb sometable -u user -p | mysql otherdb -u user -p
then type both passwords.
This works even if they are on different hosts (just add the -h parameter as usual), which you can't do with insert select.
Be careful not to accidentally pipe into the wrong db or you will end up dropping the sometable table in that db! (The dump will start with 'drop table sometable').
insert blah from select suggested by others is good for copying the data under mysql.
If you want to copy the table structure you might want to use the show create table Tablename; statement.