I am making tables in SQL Workbench. I am assuming that in SQL Workbench when a table is created it contains updated_at and created_at columns by default. Is this correct?
I am not sure whether such columns would be there by default or not.
You should check the settings. You can always check your table status by using below suggested queries:
SHOW TABLE STATUS FROM myDatabase LIKE 'myTable';
DESCRIBE myDatabase.myTable;
This link might help you:
https://dev.mysql.com/doc/workbench/en/wb-table-editor-columns-tab.html
Delete a column that you don't want by hovering the pointer over a table > right click > alter table and then make desired changes.
Work bench does not provide the created_at and updated_at columns by itself. But the MySQL as a database provides it. You can even disable it.
Related
I want a create a table that has a column updated_date that is updated to SYSDATE every time any field in that row is updated. How should I do this in Redshift?
You should be creating table definition like below, that will make sure whenever you insert the record, it populates sysdate.
create table test(
id integer not null,
update_at timestamp DEFAULT SYSDATE);
Every time field update?
Remember, Redshift is DW solution, not a simple database, hence updates should be avoided or minimized.
UPDATE= DELETE + INSERT
Ideally instead of updating any record, you should be deleting and inserting it, so takes care of update_at population while updating which is eventually, DELETE+INSERT.
Also, most of use ETLs, you may using stg_sales table for populating you date, then also, above solution works, where you could do something like below.
DELETE from SALES where id in (select Id from stg_sales);
INSERT INTO SALES select id from stg_sales;
Hope this answers your question.
Redshift doesn't support UPSERTs, so you should load your data to a temporary/staging table first and check for IDs in the main tables, which also exist in the staging table (i.e. which need to be updated).
Delete those records, and INSERT the data from the staging table, which will have the new updated_date.
Also, don't forget to run VACUUM on your tables every once in a while, because your use case involves a lot of DELETEs and UPDATEs.
Refer this for additional info.
I am new to postgreSQL. Is there any way to insert row in postgreSQL pgAdmin without using SQL Editor (SQL query)?
The accepted answer is related to PgAdmin 3 which is outdated and not supported.
For PgAdmin 4 and above, the application is running in the browser.
After you create your table, you have to make sure that your table has a primary key otherwise you couldn't edit the data as mentioned in the official documentation.
To modify the content of a table, each row in the table must be
uniquely identifiable. If the table definition does not include an OID
or a primary key, the displayed data is read only. Note that views
cannot be edited; updatable views (using rules) are not supported.
1- Add primary key
Expand your table properties by clicking on it in the pgAdmin4 legend. Right-click on 'Constraints', select 'Create' --> 'Primary Key'to define a primary key column.
2- View the data in excel like format
Browser view, right-click on your table --> select View/Edit Data --> All Rows
3- Add new row / Edit data
On the Data Output tab at the bottom of the table below the last row, there will be an empty row where you can enter new data in an excel-like manner. If you want to make updates you can also double click on any cell and change its value.
4- Save the changes
Click on the 'Save' button on the menu bar near the top of the data window.
I think some answers don't provide an answer to the original question, some of them insert records but with SQL statements and the OP clearly said WITHOUT, so I post the right answer: (Step by Step)
Alternatively you can use the query tool:
INSERT INTO public.table01(
name, age)
VALUES (?, ?);
use the lightning icon to execute.
You can do that without the SQL editor, but it's better to do this by queries.
Although, in pgAdmin, there is an option which you can click to have an excel-like window where you can add and update data in a table without using SQL language. Please select a table which you want to add a row first and click on the next icon here below.
Editing table data without primary key is forbidden
If your tables don't have a primary key or OIDs, you can view the data only.
Inserting new rows and changing existing rows isn't possible for the Edit Data tool without primary key.
Use INSERT:
INSERT INTO tablename (field1, field2) values ('value1', 2);
on pgAdmin 4, right-click on the table and use the item like below. You can also use that script in the background.
Finally, to watch the inserted data do like below. You can also use that script in the background.
All the above are correct answers. I just want to add that : When u create a table, make sure u have atleast one column as PRIMARY_KEY. Then, just follow the GUI : View/Edit data. U can add row as the last row of the table
As an update, the icon for the save button is different in pgAdmin 4.
This is how the menu should look after right-clicking on the table you want to insert into and hovering over "View/Edit Data".
After adding rows, either press F6 (on Ubuntu) or click the icon that looks like a stack of discs (database icon) with a lock on it.
Zoomed in:
Wide View:
I am using Eclipse, Java and a Derby database. I want to experiment with changing values that rewrite one of the tables in the db. Before starting the change I would like to copy the particular table (not in code) so that I can restore the original data if necessary. Sof ar googling and searching this site hasnt produced an answer. In Eclipse there is an option to export the db but it calls it a connection so I am not usre what would happen.
If you're not sure about how to connect to the database and issue sql statements, you will need to learn about JDBC. This is a good place to start.
If you're asking about the SQL, it's pretty straight forward. You can create a table based on a select statement.
e.g.
create table table2 as select * from table1 with no data;
Derby is a little strange in this area. You must specify the with no data, and the created table will be empty. You can then issue an insert that will populate the new table if you wish.
insert into table2 select * from table1;
The new table will not have indexes. You will need to create them if you want them. It might retain the primary key. You should check that if you're testing against it. If it doesn't retain the primary key, you should create the primary key before inserting data into the table.
In Eclipse there is an option to export the db but it calls it a connection so I am not sure what would happen.
If what Eclipse does isn't clear for you, you can just as well zip your entire database directory (content of DERBY_HOME env. variable) into an archive. The database must not be running while you make the backup.
I only have the basic Oracle tools available, i.e. SQL Plus, and I need to find out if a table was created with the ROWDEPENDENCIES option. It's a 10g database.
And, if it isn't set, can I use ALTER TABLE to set it, or do I have to drop and re-create the table?
SELECT owner, table_name, dependencies FROM dba_tables;
This will return "ENABLED" or "DISABLED" for each table. If you don't have access to dba_tables, query all_tables instead.
You cannot change this after the table has been created, so you'll have to re-create the table to set it on.
I have a need to change the length of CHAR columns in tables in a PostgreSQL v7.4 database. This version did not support the ability to directly change the column type or size using the ALTER TABLE statement. So, directly altering a column from a CHAR(10) to CHAR(20) for instance isn't possible (yeah, I know, "use varchars", but that's not an option in my current circumstance). Anyone have any advice/tricks on how to best accomplish this? My initial thoughts:
-- Save the table's data in a new "save" table.
CREATE TABLE save_data AS SELECT * FROM table_to_change;
-- Drop the columns from the first column to be changed on down.
ALTER TABLE table_to_change DROP column_name1; -- for each column starting with the first one that needs to be modified
ALTER TABLE table_to_change DROP column_name2;
...
-- Add the columns back, using the new size for the CHAR column
ALTER TABLE table_to_change ADD column_name1 CHAR(new_size); -- for each column dropped above
ALTER TABLE table_to_change ADD column_name2...
-- Copy the data bace from the "save" table
UPDATE table_to_change
SET column_name1=save_data.column_name1, -- for each column dropped/readded above
column_name2=save_date.column_name2,
...
FROM save_data
WHERE table_to_change.primary_key=save_data.primay_key;
Yuck! Hopefully there's a better way? Any suggestions appreciated. Thanks!
Not PostgreSQL, but in Oracle I have changed a column's type by:
Add a new column with a temporary name (ie: TMP_COL) and the new data type (ie: CHAR(20))
run an update query: UPDATE TBL SET TMP_COL = OLD_COL;
Drop OLD_COL
Rename TMP_COL to OLD_COL
I would dump the table contents to a flat file with COPY, drop the table, recreate it with the correct column setup, and then reload (with COPY again).
http://www.postgresql.org/docs/7.4/static/sql-copy.html
Is it acceptable to have downtime while performing this operation? Obviously what I've just described requires making the table unusable for a period of time, how long depends on the data size and hardware you're working with.
Edit: But COPY is quite a bit faster than INSERTs and UPDATEs. According to the docs you can make it even faster by using BINARY mode. BINARY makes it less compatible with other PGSQL installs but you won't care about that because you only want to load the data to the same instance that you dumped it from.
The best approach to your problem is to upgrade pg to something less archaic :)
Seriously. 7.4 is going to be removed from "supported versions" pretty soon, so I wouldn't wait for it to happen with 7.4 in production.