Added asciidoc document, trying to create a nice document for migrations

migrationsExamples.txt

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+== Groovy Liquibase migrations examples
+
+Created by Erwin van Brandwijk
+
+Company http://www.42.nl/[42bv Netherlands]
+
+This document contains all changes from Liquibase that can be executed with Groovy-Liquibase. These are the examples from liquibase.org/manuel. I have converted them to groovy changes. After that I tested them on
+PostgreSQL and some on Mysql.
+
+.Example: changelogFile
+----
+databaseChangeLog() {
+  // changeSets
+}
+----
+
+If quotes are empty, you do not have to use that parameter. See example with addColumn - schemaName.
+.Example: Add Column
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = yes")
+
+  addColumn(tableName: "books", schemaName: "") {
+    column(name: "firstname", type: "varchar(255)")
+  }
+}
+----
+
+Could be ...
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = yes")
+
+  addColumn(tableName: "person") {
+    column(name: "firstname", type: "varchar(255)")
+  }
+}
+----
+
+If the comment tag contains rollback = no, you will have to create your own rollback. You have got two
+possibilities. See next example....
+.Example: Drop Column with own rollback
+----
+changeSet(author: "erwin", id: "4") {
+  comment("rollback = no")
+
+  dropColumn(tableName: "Person", columnName: "test")
+
+  rollback{
+    addColumn(tableName: "Person") {
+      column(name: "test", type: "varchar(255)")
+    }
+//of SQL in rollback
+  rollback(“””
+        //SQL QUERY;
+  “””)
+}
+----
+
+Do Not use groovy outside a (custom) groovy change, this will always be executed!! Unless you want that.
+When using a Boolean or integer, don't use quotes example: nullable: false
+
+
+.Add column
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = yes")
+
+  addColumn(tableName: "persons", schemaName: "") {
+    column(name: "boss", type: "int") {
+      constraints(nullable: false, foreignKeyName:
+      "FK_persons_boss_persons_id", references: "persons(id)")
+    }
+  }
+  //      possible parameters → Column
+  // String name, String type, String value, Number valueNumeric, Date valueDate,
+  // Boolean valueBoolean, String defaultValue, Number defaultValueNumeric,
+  // Date defaultValueDate, Boolean defaultValueBoolean,
+  // DatabaseFunction defaultValueComputed, Boolean autoIncrement, String remarks
+
+  //      possible parameters → Constraints
+  // Boolean nullable, Boolean primaryKey, String primaryKeyName,
+  // String primaryKeyTablespace, String references, Boolean unique,
+  // String uniqueConstraintName, String check, Boolean deleteCascade,
+  // String foreignKeyName, Boolean initiallyDeferred, Boolean deferrable
+}
+----
+
+
+.Rename column
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = yes")
+
+  renameColumn(tableName: "test", oldColumnName: "testcolumn", schemaName: "",
+  newColumnName: "testrenamecolumn", columnDataType: "int")
+}
+----
+
+.Modify datatype
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = yes")
+
+  modifyDataType(tableName: "test", clumnName: "testcolumn", schemaName: "",
+  newDataType: "int")
+}
+----
+
+.Drop column
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = no")
+
+  dropColumn(tableName: "person", schemaName: "", columnName: "testcolumn")
+}
+----
+
+.Alter sequence
+----
+changeSet(author: "erwin", id: "1") {
+  comment("rollback = no")
+
+  alterSequence(sequenceName: "seq_employee_id", incrementBy: "10")
+}
+----