Bases De Datos

Equivalencias MySQL - PostgreSQL

Perl DBI

MySQL	PostgreSQL
$db=DBI→connect(“dbi:mysql:database= … )	$db=DBI→connect(“dbi:Pg:database= … )

Sintaxis y lenguaje

MySQL	PostgreSQL
SHOW FULL PROCESSLIST / SHOW PROCESSLIST	SELECT * FROM pg_stat_activity
#	–
… WHERE lastname=“smith”	… WHERE lower(lastname)='smith'
DESCRIBE tablename	\d tablename
DROP TABLE IF EXISTS	DROP TABLE IF EXISTS
SELECT … INTO OUTFILE '/var/tmp/outfile'	COPY ( SELECT … ) TO '/var/tmp/outfile'
SHOW DATABASES	\l
SHOW TABLES	\dt

Tipos de datos

MySQL	PostgreSQL	comments
TINYINT SMALLINT MEDIUMINT BIGINT	SMALLINT SMALLINT INTEGER BIGINT	see [2]; `integer` size in PostgreSQL is 4 Bytes signed (-2147483648 – +2147483647)
TINYINT UNSIGNED SMALLINT UNSIGNED MEDIUMINT UNSIGNED INT UNSIGNED BIGINT UNSIGNED	SMALLINT INTEGER INTEGER BIGINT NUMERIC(20)	SQL doesn't know `UNSIGNED`, all numbers are signed.
ZEROFILL		No replacement.
DOUBLE	DOUBLE PRECISION
BOOLEAN	BOOLEAN	MySQL Booleans are an alias for TINYINT(1); PostgreSQL doesn't auto-convert numbers into booleans.
DATE TIME DATETIME	DATE TIME TIMESTAMP
TIMESTAMP NOT NULL DEFAULT NOW()	TIMESTAMP NOT NULL DEFAULT NOW()
LONGTEXT MEDIUMTEXT BLOB	TEXT TEXT BYTEA	TEXT
columnname INT AUTO_INCREMENT	columnname SERIAL equals to: CREATE SEQUENCE tablename_columnname_seq; CREATE TABLE tablename ( columnname INT4 NOT NULL DEFAULT nextval('tablename_columnname_seq') );	SERIAL = 1 – 2147483647BIGSERIAL = 1 – 9223372036854775807 SERIAL is in fact an entity named SEQUENCE. It exists independently on the rest of your table. If you want to cleanup your system after dropping a table, you also have to `DROP SEQUENCE tablename_columnname_seq`. More on that topic...
field ENUM (val_1, val_2, ...)	field VARCHAR(255) NOT NULL, CHECK (field IN (val_1, val_2, ...)) OR CREATE TYPE mood AS ENUM ('sad','ok','happy'); CREATE TABLE person ( current_mood mood ...	PostgreSQL doesn't have the ENUM types prior to 8.3, so you need to simulate it with contraints when using < 8.3.

Ref.: http://en.wikibooks.org/wiki/Converting_MySQL_to_PostgreSQL

Tips MySQL

Borrar todas las tablas de una base de datos

MYSQL="mysql -h HOST -u USERNAME -pPASSWORD -D DB_NAME"
$MYSQL -BNe "show tables" | awk '{print "set foreign_key_checks=0; drop table `" $1 "`;"}' | $MYSQL
unset MYSQL

También podemos usar la sintaxys LIKE para borrar solo algunas tablas que concuerden con algún patrón, útil cuando tenemos un programa que genera muchas tablas con un timestamp añadido

show tables like 'ifvolume_1%'

Replicacion facil

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

old_passwords=1
log_bin = /var/log/mysql/mysql-bin.log
relay-log = /var/log/mysql/mysql-relay.log
max_binlog_size = 100M

expire_logs_days        = 2
max_binlog_size         = 100M

log-bin
binlog-do-db=proxyauth
skip-slave-start

server-id=1
replicate-do-db=base
replicate-do-table=base.tabla

master-host=10.1.1.1
master-user=root
master-password=contraseña
master-port=3306

[mysql.server]
user=mysql
basedir=/var/lib

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock

old_passwords=1
log_bin = /var/log/mysql/mysql-bin.log
relay-log = /var/log/mysql/mysql-relay.log
max_binlog_size = 100M

expire_logs_days        = 2
max_binlog_size         = 100M

log-bin
binlog-do-db=proxyauth
skip-slave-start

server-id=2
replicate-do-db=base
replicate-do-table=base.tabla

master-host=10.1.1.2
master-user=root
master-password=contraseña
master-port=3306

[mysql.server]
user=mysql
basedir=/var/lib

skip-slave-start Es para tener que hacer el start slave; manualmente (por si las dudas).

Importar/Exportar CSV

Importacion :

LOAD DATA LOCAL INFILE 'usuarios.csv'
INTO TABLE usuarios
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
(nombre, pass, usuario);

Exportacion :

SELECT * FROM usuarios ORDER BY DATE DESC
INTO OUTFILE "usuarios.csv"
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
LINES TERMINATED BY '\r\n';

mysql -u root -p  cdr -B -e  "select * from \`calldetails\` limit 2;" | sed 's/\t/","/g;s/^/"/;s/$/"/;s/\n//g'

Oracle

Oracle XE issues

Oracle xe must be the buggiest free counterpart of a commercial product ever released.Here's a list of issues and solutions encountered on Ubuntu 10.04 so far.Few config tips first.

I don't set up it to be started upon boot (don't want this bag of bugs eat my memory)
change the default apex port from 8080 to smth else
use 8+ characters for sys/system password
check status of the DB: $ sudo /etc/init.d/oracle-xe status
start the DB - I use restart just to be sure: $ sudo /etc/init.d/oracle-xe restart

Q: After installing and sourcing /usr/lib/oracle/xe/app/oracle/product/10.2.0/server/bin/oracle_env.sh I was getting /usr/lib/oracle/xe/app/oracle/product/10.2.0/server/bin/nls_lang.sh: 114: [[: not found each time starting a shell

A: Change the nls_lang.sh to use your shell (/bin/bash) instead of /bin/sh on top of the script.

Q: after installing oracle xe I cannot login to apex (oracle web admin) under sys or system. It won't accept my login/password. Keeps saying access denied although I'm sure the password is correct (the one used during /etc/init.d/oracle-xe configure)

A: Use a longer password! It won't complain but seems like it doesn't like short passwords. Use at least 8 chars.Q:After some time your oracle connected application runs into

ORA-12519, TNS:no appropriate service handler found

A: Run the following statement from sqlplus or web admin (you should have it accessible due to above tips)

ALTER SYSTEM SET PROCESSES=150 SCOPE=SPFILE;

Found here

Q: How to remove oracle user from ubuntu desktop login screen.

A: Change the oracle's UID to smth below 1000.

$ sudo usermod –gid 999 oracle

After that change the ownership of the files in /var/tmp/.

oracle$ sudo chown -R oracle:dba /var/tmp/.oracle/

or you won't be able to start the DB anymore :)

Q: Cannot open Oracle web interface, Page cannot be displayed. Used to work before, and the DB is working.

A: Might happen especially if you selected to start the DB manually rather than on each boot. The symptoms might be a bit different, the DB might be started or might be not. Some services just fail to start.

Try restart :

$ sudo /etc/init.d/oracle-xe restart or $ sudo /etc/init.d/oracle-xe force-reload

Fuente: http://ubuntu-answers.blogspot.com/2010/10/oracle-xe-issues.html