问题

I am wondering on how to generate scripts (DDL, DML) from an specific template to different databases, like Oracle, MSSQL, Sybase.

Liquibase seems to fit, but is there any framework or way to do it?

回答1:

The following example generates SQL for the H2 database. The XML changeset enables liquibase to generate database specific SQL.

Example

Install the jars

mkdir lib
curl http://search.maven.org/remotecontent?filepath=org/liquibase/liquibase-core/3.0.8/liquibase-core-3.0.8.jar -o lib/liquibase.jar
curl http://search.maven.org/remotecontent?filepath=com/h2database/h2/1.3.174/h2-1.3.174.jar -o lib/h2.jar

This is a cheat. You could also download and install the zip package.

Sample changelog file

This changelog creates a single table. The following format is XML, other supported formats are YAML and SQL.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<databaseChangeLog
    xmlns="http://www.liquibase.org/xml/ns/dbchangelog"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ext="http://www.liquibase.org/xml/ns/dbchangelog-ext"
    xsi:schemaLocation="http://www.liquibase.org/xml/ns/dbchangelog http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-2.0.xsd
    http://www.liquibase.org/xml/ns/dbchangelog-ext http://www.liquibase.org/xml/ns/dbchangelog/dbchangelog-ext.xsd">

    <changeSet author="mark" id="1">
        <createTable tableName="EMPLOYEE">
            <column name="EMPNO" type="INT">
                <constraints nullable="false" primaryKey="true" primaryKeyName="EMP_PK"/>
            </column>
            <column name="NAME" type="VARCHAR(10)"/>
            <column name="JOB" type="VARCHAR(9)"/>
            <column name="BOSS" type="INT"/>
            <column name="HIREDATE" type="VARCHAR(12)"/>
            <column name="SALARY" type="DECIMAL(7,2)"/>
            <column name="COMM" type="DECIMAL(7,2)"/>
            <column name="DEPTNO" type="INT"/>
        </createTable>
    </changeSet>

</databaseChangeLog>

Running

Liquibase can be run as follows to generate the SQL

java -jar ./lib/liquibase.jar \
     --classpath=lib/h2.jar \
     --url=jdbc:h2:db/scottTiger \
     --driver=org.h2.Driver \
     --username=user \
     --password=pass \
     --changeLogFile=sample.xml \
     updateSQL

The "update" command would apply the SQL against the database.

Generated output

-- *********************************************************************
-- Update Database Script
-- *********************************************************************
-- Change Log: sample.xml
-- Ran at: 22/12/13 22:30
-- Against: USER@jdbc:h2:db/scottTiger
-- Liquibase version: 3.0.8
-- *********************************************************************

-- Create Database Lock Table
CREATE TABLE PUBLIC.DATABASECHANGELOGLOCK (ID INT NOT NULL, LOCKED BOOLEAN NOT NULL, LOCKGRANTED TIMESTAMP, LOCKEDBY VARCHAR(255), CONSTRAINT PK_DATABASECHANGELOGLOCK PRIMARY KEY (ID));

-- Initialize Database Lock Table
DELETE FROM PUBLIC.DATABASECHANGELOGLOCK;

INSERT INTO PUBLIC.DATABASECHANGELOGLOCK (ID, LOCKED) VALUES (1, FALSE);

-- Lock Database
-- Create Database Change Log Table
CREATE TABLE PUBLIC.DATABASECHANGELOG (ID VARCHAR(255) NOT NULL, AUTHOR VARCHAR(255) NOT NULL, FILENAME VARCHAR(255) NOT NULL, DATEEXECUTED TIMESTAMP NOT NULL, ORDEREXECUTED INT NOT NULL, EXECTYPE VARCHAR(10) NOT NULL, MD5SUM VARCHAR(35), DESCRIPTION VARCHAR(255), COMMENTS VARCHAR(255), TAG VARCHAR(255), LIQUIBASE VARCHAR(20));

-- Changeset sample.xml::1::mark
CREATE TABLE PUBLIC.EMPLOYEE (EMPNO INT NOT NULL, NAME VARCHAR(10), JOB VARCHAR(9), BOSS INT, HIREDATE VARCHAR(12), SALARY DECIMAL(7, 2), COMM DECIMAL(7, 2), DEPTNO INT, CONSTRAINT EMP_PK PRIMARY KEY (EMPNO));

INSERT INTO PUBLIC.DATABASECHANGELOG (ID, AUTHOR, FILENAME, DATEEXECUTED, ORDEREXECUTED, MD5SUM, DESCRIPTION, COMMENTS, EXECTYPE, LIQUIBASE) VALUES ('1', 'mark', 'sample.xml', NOW(), 1, '7:4700326f252366e9cfe598fded5037c8', 'createTable', '', 'EXECUTED', '3.0.8');

Liquibase creates a special table called "DATABASECHANGELOG" to track all changes. Look carefully and you'll find the table create statement for the "EMPLOYEE" table.

This example if for H2. Other databases are supported.

来源：https://stackoverflow.com/questions/20733777/best-choice-to-generate-scripts-for-different-databases

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