Sunday, December 30, 2012

PostgreSQL - Copy CSV to table with psql - part 2


CREATE TABLE tbl_test
(
 a text,
 b text,
 c text
)
Content of test.csv, and it put in /Database folder
a1,b1,c1
a2,b2,c2
a3,b3,c3


Instead of using COPY command directly, you can modify the test.cvs file to include it, as
COPY tbl_test FROM STDIN WITH CSV;
a1,b1,c1
a2,b2,c2
a3,b3,c3

\.

Note that you have to include a carriage return in the last line of the file (after '\.')
Then, run the following command to import

MyComputer$ psql -h localhost -p 5432 -U postgres testdb -f ~/Database/test.csv

Thursday, December 13, 2012

PostgreSQL - Copy database

Sometimes, instead of back up and restore to a new db and wait your time if you only want to copy a database and put in the same server, you can use the following query:

CREATE DATABASE newdb WITH TEMPLATE originaldb OWNER dbuser;
Note that this query only successfully if no sessions existing in originaldb. So, you can check originaldb sessions and kill them with this function pg_terminate_backend(procpid)

PostgreSQL - Kill idle processes

Sometimes, you need to kill all unnecessary processes running on your database server. You can do that by using the following query:

SELECT           
   procpid,
   (
       SELECT pg_terminate_backend(procpid)
   ) AS killed
 FROM pg_stat_activity
 WHERE current_query LIKE '%idle%' AND datname = 'YourDBName';

Sunday, December 9, 2012

PostgreSQL - Copy csv file to table with psql

CREATE TABLE tbl_test
(
 a text,
 b text,
 c text
)
Content of test.csv
a1,b1,c1
a2,b2,c2
a3,b3,c3

psql to COPY
psql -h localhost -U postgres testdb
testdb=# COPY tbl_test FROM 'D:\Temp\test.csv' WITH DELIMITER ',' CSV; 

PostgreSQL - VACUUM ANALYZE EXPLAIN NOTIFY

Select the correct statement that records the space occupied by deleted or updated rows for later reuse, and also updates statistics.

A. VACUUM
B. VACUUM ANALYZE
C. EXPLAIN
D. EXPLAIN ANALYZE
E. NOTIFY
F. None of the above

Answer: [B]
Highlight to find out the answer.

PostgreSQL - ANALYZE quiz

What does the following command do?
Choose the correct answer below.
Note: "psql=#" is the command prompt for psql.
psql=# ANALYZE xyz;

A. Collects statistical information related to the content of the database xyz.
B. Collects statistical information related to the content of the table xyz.
C. Outputs statistical information related to the content of the table xyz.
D. No ANALYZE command in PostgreSQL, error will occur.
E. None of the above
F. Both B & C

Answer: [B]
Highlight to find out the answer.

Friday, December 7, 2012

PostgreSQL – Convert rows to string

SELECT array_to_string(
    array(
        SELECT name
        FROM pg_settings
        WHERE setting = 'off' AND context = 'postmaster'
    ), ',');

SELECT setting, array_to_string(array_agg(name), ',')
FROM pg_settings
WHERE setting IN ('on', 'off')
GROUP BY setting;

Saturday, November 24, 2012

PostgreSQL - Query data from another database/server

Assume that, you have two databases:
1. db1 with two schemas: public and sch1
2. db2 with two schemas: public and sch2

In PostgreSQL, you can access a table from a different schema by using SELECT * FROM schema_name.table_name such as SELECT * FROM db1_sch.employee;
However, you cannot access a table on the different database with explicit way like SELECT * FROM db2.sch2.employee;

The question is how can we access like SQL Server or some other DBMS.
Fortunately, PostgreSQL support dblink to do that.

First, install extension dblink on the database you want to be able to access to other
CREATE EXTENSION dblink;

If db2 is in the same server, you can query table in db2 like that:
SELECT *
FROM dblink('dbname=db2', 'SELECT employee_id, employee_name FROM sch2.employee')
           AS employee(employee_id integer, employee_name text);

If db2 is in the different server, you can query:
SELECT *
FROM dblink('hostaddr=172.x.x.x dbname=db2 user=admin password=pwd port=5432', 'SELECT employee_id, employee_name FROM sch2.employee')
           AS employee(employee_id integer, employee_name text);

Monday, November 5, 2012

PostgreSQL - get table structure

SELECT ordinal_position
, column_name
, CASE data_type WHEN 'character varying' THEN data_type || '('||character_maximum_length || ')' ELSE data_type END data_type
, column_default
, is_nullable
, character_maximum_length
, numeric_precision
FROM information_schema.columns
WHERE table_catalog = 'database_name'
AND table_schema = 'schema_name'
AND table_name = 'table_name'
ORDER BY ordinal_position;

Friday, October 19, 2012

PostgreSQL: check the core settings of server

SELECT name, context, unit, setting, short_desc

FROM pg_settings

WHERE name in ('listen_addresses' ,'max_connections' ,'shared_buffers' ,'effective_cache_size' , 'work_mem' , 'maintenance_work_mem')

ORDER BY context,name;

image

If context is set to postmaster, it means changing this parameter requires a restart of the postgresql service. If context is set to user, changes require at least a reload. Furthermore, these settings can be            overridden at the database, user, session, or function levels.

unit tells you the unit of measurement that the setting is reported in. This is very important for memory settings since, as you can see, some are reported in 8 kB and some in kB

Thursday, October 18, 2012

PosgreSQL: get main configuration files

SELECT name, setting FROM pg_settings WHERE category = 'File Locations';

image

postgresql.conf controls general settings, such as how much memory to allocate, default storage location for new databases, which IPs PostgreSQL listens on, where logs are stored, and so forth.

pg_hba.conf controls security. It manages access to the server, dictating which users can login into which databases, which IPs or groups of IPs are permitted to connect and the authentication scheme expected.

pg_ident.conf is the mapping file that maps an authenticated OS login to a PostgreSQL user. This file is used less often, but allows you to map a server account to a PostgreSQL account. For example, people sometimes map the OS root account to the postgre’s super user account. Each authentication line in pg_hba.conf can use a different pg_ident.conf file

Wednesday, October 17, 2012

PostgreSQL quiz: stored procedure execution

Assume that you have a table contact and a stored procedure called insert_contact as the following screenshots

image

image

Which one below is correct?

A. CALL insert_contact(‘John’,'Tran’);

B. EXECUTE insert_contact(‘John’,’Tran’);

C. SELECT insert_contact(‘John’,’Tran’)

D. Both A & B

E. Error in the store procedure code

F. None of the above

 

Answer: [C]

Highlight to find out the answer.

Tuesday, October 16, 2012

PostgreSQL license

Select the most suitable statement about the PostgreSQL license from below.


A. PostgreSQL is distributed under the GPL license.
B. PostgreSQL is distributed under the PostgreSQL license.
C. PostgreSQL is distributed under the LGPL license.
D. PostgreSQL is distributed under the BSD license.
E. PostgreSQL is distributed under the X11(MIT) license.

 

Answer: [D]

Highlight to find out the answer.

Monday, October 15, 2012

Convert date time values to string in PostgreSQL

This is a view extracted from OpenERP.

CREATE OR REPLACE VIEW crm_claim_report
AS
SELECT min(c.id) AS id
, to_char(c.date, 'YYYY'::text) AS name
, to_char(c.date, 'MM'::text) AS month
, to_char(c.date, 'YYYY-MM-DD'::text) AS day
, to_char(c.date_closed, 'YYYY-MM-DD'::text) AS date_closed
, to_char(c.date_deadline::timestamp with time zone, 'YYYY-MM-DD'::text) AS date_deadline, c.state, c.user_id
, c.stage_id, c.section_id, c.partner_id, c.company_id, c.categ_id, count(*) AS nbr, c.priority
, c.type_action, date_trunc('day'::text, c.create_date) AS create_date
, avg(date_part('epoch'::text, c.date_closed - c.create_date)) / (3600 * 24)::double precision AS delay_close
, ( SELECT count(mailgate_message.id) AS count FROM mailgate_message
WHERE mailgate_message.model::text = 'crm.claim'::text AND mailgate_message.res_id = c.id AND mailgate_message.history = true) AS email
, ( SELECT avg(crm_case_stage.probability) AS avg FROM crm_case_stage
WHERE crm_case_stage.type::text = 'claim'::text AND crm_case_stage.id = c.stage_id) AS probability
, date_part('epoch'::text, c.date_deadline::timestamp without time zone - c.date_closed) / (3600 * 24)::double precision AS delay_expected
FROM crm_claim c
GROUP BY to_char(c.date, 'YYYY'::text), to_char(c.date, 'MM'::text), to_char(c.date, 'YYYY-MM-DD'::text), c.state, c.user_id, c.section_id
, c.stage_id, c.categ_id, c.partner_id, c.company_id, c.create_date, c.priority, c.type_action, c.date_deadline, c.date_closed, c.id;

Sunday, October 14, 2012

PostgreSQL Contactenation

Which query is correct in PostgreSQL?

A. SELECT 'Test' . 'query';
B. SELECT cat('Test','query') FROM dual;
C. SELECT 'Test' + 'query';
D. SELECT 'Test' + 'query' FROM dual;
E. SELECT 'Test' || 'query';

Answer:[E]
Highlight to find out the answer.

Friday, October 12, 2012

Same query for Fiscal and Normal calendar

tblFiscalMapping

image

Assume that you have a mapping table between Fiscal and Normal calendar above.

Sometimes, you need to write one stored procedure with a param @IsFiscal to determine when to return order info on Fiscal year or Normal calendar year.

You can implement as the following

DECLARE @StartMonth SMALLDATETIME;   
DECLARE @EndMonth SMALLDATETIME;

IF ISNULL(@IsFiscal,0) = 0
    SELECT @StartMonth = CAST(CAST(@Year AS VARCHAR) + '-01-01' AS SMALLDATETIME);
ELSE
    SELECT @StartMonth = CAST(CAST([Year] AS VARCHAR) + '-' + CAST(NormalMonth AS VARCHAR) + '-01' AS SMALLDATETIME)
    FROM dbo.tblFiscalMapping
    WHERE FiscalYear = @Year;

SET @EndMonth = DATEADD(m, 11, @StartMonth);

SELECT OrderID, OrderNumber, OrderDate, CustomerID, TotalAmount

FROM dbo.tblOrder

WHERE DATEDIFF(m, @StartMonth, OrderDate) >= 0
                                AND DATEDIFF(m, @EndMonth, OrderDate) <= 0

Create a Virtual Active Directory Domain Controller with VirtualBox

I need to query Active Directory by using SQL Server, so I created virtual Active Directory Domain Controller to do that.

1. Install Windows Server virtual machine, such as Windows Server 2003

2. Install Client virtual machine, such as Windows XP

3. Set up network

image

image

4. Set up new Adapter for each machine, use the adapter set up on Step 3

image

5. Run Windows Server machine

6. Install Active Directory by following steps after running dcpromo

image

7. Set up IP Address on Windows Server, note that IP address must be in the range set up in Step 3

image

8. Set up IP Address on Client machine

image

9. Create a domain user for client machine in Domain Controller

To allow domain user as local admin, please visit this link

10. Register client machine in domain controller which is defined in Step 6, then input user name/pwd defined in Step 9

image

Tuesday, October 9, 2012

Create SQL Server linked server to PostgreSQL database

1. Download ODBC Driver at this address http://www.postgresql.org/ftp/odbc/versions/msi/

Choose the suitable version with your PostgreSQL database. I’m using PostgreSQL 9, so I chose latest version. (^_^)

image

2. Install ODBC Driver for PostgreSQL

image

image

3. Create connection to PostgreSQL database with ODBC Driver

image

image

image

image

4. Now, it’s time to create linked server to PostgreSQL database:

You can create with GUI

image

Or can create with scripts

EXEC master.dbo.sp_addlinkedserver @server = N'OPENERP', @srvproduct=N'PostgreSQL', @provider=N'MSDASQL', @datasrc=N'OpenERP';

GO
EXEC master.dbo.sp_addlinkedsrvlogin @rmtsrvname=N'OPENERP',@useself=N'False',@locallogin=NULL,@rmtuser=NULL,@rmtpassword=NULL;

GO

Finally, you can query PostgreSQL database inside SQL Server

image

5. Verify the linked server

image

Query Excel spreadsheet on SQL Server 2008 64 bit with Linked Server

For SQL Server 64 bit, if you use Microsoft.Jet.OLEDB.4.0, you may experience this issue:

OLE DB provider 'Microsoft.Jet.OLEDB.4.0' cannot be used for distributed queries because the provider is configured to run in single-threaded apartment mode.

To fix this, please follow the following:

1. Download and install Microsoft Access Database Engine 2010 Redistributable at this address http://www.microsoft.com/en-us/download/details.aspx?id=13255 

image

2. After installing, create a linked server to your Excel file

EXEC master.dbo.sp_addlinkedserver @server = N'EXCEL_LINKED_SERVER_NAME'
                    , @srvproduct=N'Excel'
                    , @provider=N'Microsoft.ACE.OLEDB.12.0'
                    , @datasrc=N'C:\Your_Excel_File.xls'
                    , @provstr=N'Excel 12.0';

GO

EXEC master.dbo.sp_addlinkedsrvlogin @rmtsrvname=N'EXCEL_LINKED_SERVER_NAME',@useself=N'False',@locallogin=NULL,@rmtuser=NULL,@rmtpassword=NULL;

GO

3. Run OPENQUERY to get data from your Excel file

SELECT * FROM OPENQUERY(EXCEL_LINKED_SERVER_NAME,'SELECT * FROM [Sheet1$]')

Monday, October 8, 2012

Get current queries executing on PostgreSQL

SELECT datname "Database Name"
 , usename "User Name"
 , procpid "Process ID"
 , client_addr "Client IP Address"
 , waiting "Is waiting"
 , query_start "Start Time"
 , current_query "Query Text"
FROM pg_stat_activity;

Get current queries executing on SQL Server

SELECT t1.session_id
 , t2.text
, t1.[status]
, t1.blocking_session_id
, t1.cpu_time
, t1.total_elapsed_time  
FROM sys.dm_exec_requests t1  
     CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS t2

Sunday, September 30, 2012

Scrum project management in OpenERP

OpenERP allows you to manage your projects by using scrum methodology: projects with sprints, product owner, scrum master, product backlog, scrum meeting, etc.

Here’s some screenshots

image

List of product backlogs/features

image

Product backlog detail: each backlog/feature belongs to a sprint, and contains many tasks

image

Sprint detail

image

Scrum meeting

image

Scrum dashboard

image

For database perspective, you can consider the following tables

image

Agile: A good introduction

Saturday, September 29, 2012

Stored procedure: why use & why not use

Use Stored Procedure
● Reusability
– Avoid rewriting sub queries and improve readability.
– If you can't store a query in a library that all the applications can access, you can put that query in a stored procedure.
● Separation of duties
– You don't trust non-DBA's to write queries.
● Data integrity
– Use triggers or constraints to prevent bad data from entering.
– Run several interdependent queries in a transaction in a single stored procedure.
● Event handling
– Log changes.
– Notify other systems of new data.

Not Use Stored Procedure
● Views may be all you need.
● An object-relational mapping (ORM) can help write queries safely.
● Difficult to version control stored procedures.
● Software rollouts may require more db changes.
● Could slow software development process.

Inspecting your postgreSQL connection information

If you want to confirm you've connected to the right place and in the right way, you can execute some or all of the following commands:

SELECT inet_server_port();  
SELECT current_database();  
SELECT current_user;  
SELECT inet_server_addr();  
SELECT version();

Backup/Restore postgresSQL database with pgAdmin

BACKUP

1. Choose database need to backup

image

2. Save to backup file, choose COMPRESS as default

image

The GUI actually calls pg_dump command to do the backup

image

Choose Done to complete. You can see the backup file in selected folder

The backup as COMPRESS, so it cannot be read with text editor

image

If you want the backup is readable, you can choose backup type is PLAIN

image

image

 

RESTORE

1. Create an empty database

2. Choose the created database, and choose Restore

image

3. Select the backup file

image

The GUI actually calls pg_restore command to do the restore

image

4. Click OK to get the task execute. Database is restored to a new one.

Friday, September 28, 2012

Join quiz 1

image
Look at the above picture and choose the correct answer:
A. SELECT * FROM TableA t1 INNER JOIN TableB t2 ON t1.ID = t2.ID
B. SELECT * FROM TableA t1 LEFT JOIN TableB t2 ON t1.ID = t2.ID
C. SELECT * FROM TableA t1 RIGHT JOIN TableB t2 ON t1.ID = t2.ID
D. SELECT * FROM TableA t1, TableB t2 WHERE t1.ID = t2.ID
E. Both A and D
F. None of the above

Answers: [E]


Psql Help in PostgreSQL



My bat files to start/stop OpenERP services

Start OpenERP

@PATH=%WINDIR%\system32;%WINDIR%;%WINDIR%\System32\Wbem;.
@net start openerp-server-6.0
@net start openerp-web-6.0
@net start postgresql-9.0
pause

 

Stop OpenERP

@PATH=%WINDIR%\system32;%WINDIR%;%WINDIR%\System32\Wbem;.
@net stop openerp-server-6.0
@net stop openerp-web-6.0
@net stop postgresql-9.0
pause

Sunday, September 23, 2012

Install OpenERP step by step

After installing server, web client, and GTK client

image

Open OpenERP Client, no database installed at this time

image

Create new database

image

image

image

Choose Extended for more options

image

For my research purpose, I installed everything

image

Follow the next steps in the wizard, you can finish the installation. Enjoy!

Saturday, September 15, 2012

Get rows without duplicate values

CREATE TABLE T1(a INT,b INT,c INT)
INSERT INTO T1(a,b,c)
SELECT 1,2,3
UNION
SELECT 2,2,4
UNION 
SELECT 3,3,3
UNION
SELECT 4,3,5
 
SELECT *
FROM T1
WHERE a NOT IN (SELECT MAX(a)
                FROM T1
                GROUP BY b)

Tuesday, March 6, 2012

Unlock an account

From your command prompt, type
SQLPlus "/ as SYSDBA"

SQL> ALTER USER scott ACCOUNT UNLOCK;
Make sure to execute the following command
SQL> COMMIT;

Oracle Query