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# Database Upgrades
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Version-specific database migration utilities supporting upgrades between Liferay 7.x versions with comprehensive schema transformation capabilities and data migration procedures.
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## Capabilities
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### Upgrade Utilities
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Common utilities for database schema upgrades and data migrations.
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```java { .api }
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/**
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 * Base upgrade process providing common upgrade functionality
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 */
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public abstract class UpgradeProcess {
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    /**
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     * Executes the upgrade process
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     * @throws UpgradeException if upgrade fails
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     */
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    public abstract void upgrade() throws UpgradeException;
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    /**
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     * Gets upgrade step description
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     * @return description of what this upgrade does
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     */
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    public abstract String getDescription();
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    /**
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     * Checks if upgrade is applicable to current schema
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     * @return true if upgrade should be executed
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     */
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    protected boolean isApplicable();
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    /**
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     * Executes SQL statements for schema changes
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     * @param sql SQL statements to execute
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     * @throws SQLException if SQL execution fails
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     */
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    protected void runSQL(String... sql) throws SQLException;
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    /**
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     * Alters table structure
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     * @param tableName table to alter
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     * @param alterStatement SQL alter statement
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     * @throws SQLException if alter fails
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     */
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    protected void alterTable(String tableName, String alterStatement) throws SQLException;
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}
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```
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### Liferay 7.0.0 Upgrades
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Version-specific upgrade implementations for Liferay 7.0.0 migration procedures.
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```java { .api }
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/**
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 * Upgrade processes for Liferay 7.0.0 migration
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 */
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public class UpgradeSchema_7_0_0 extends UpgradeProcess {
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    /**
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     * Upgrades database schema to Liferay 7.0.0 format
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     * @throws UpgradeException if schema upgrade fails
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     */
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    @Override
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    public void upgrade() throws UpgradeException;
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}
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/**
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 * Data migration for Liferay 7.0.0 upgrade
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 */
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public class UpgradeData_7_0_0 extends UpgradeProcess {
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    /**
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     * Migrates data to Liferay 7.0.0 compatible format
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     * @throws UpgradeException if data migration fails
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     */
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    @Override
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    public void upgrade() throws UpgradeException;
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}
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```
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### Liferay 7.0.5 Upgrades
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Version-specific upgrade implementations for Liferay 7.0.5 migration procedures.
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```java { .api }
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/**
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 * Upgrade processes for Liferay 7.0.5 migration
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 */
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public class UpgradeSchema_7_0_5 extends UpgradeProcess {
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    /**
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     * Upgrades database schema to Liferay 7.0.5 format
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     * @throws UpgradeException if schema upgrade fails
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     */
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    @Override
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    public void upgrade() throws UpgradeException;
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}
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```
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### Liferay 7.1.x Upgrades
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Version-specific upgrade implementations for Liferay 7.1.x migration procedures.
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```java { .api }
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/**
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 * Upgrade processes for Liferay 7.1.x migration
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 */
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public class UpgradeSchema_7_1_x extends UpgradeProcess {
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    /**
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     * Upgrades database schema to Liferay 7.1.x format
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     * @throws UpgradeException if schema upgrade fails
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     */
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    @Override
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    public void upgrade() throws UpgradeException;
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}
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```
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## Usage Examples
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**Running Database Upgrades:**
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```java
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// Execute upgrade process
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UpgradeProcess upgrade = new UpgradeSchema_7_0_0();
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if (upgrade.isApplicable()) {
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    upgrade.upgrade();
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}
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```
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## Integration with Portal Framework
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Database upgrades integrate with:
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- **Portal Startup** - Automatic upgrade detection and execution
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- **Data Migration** - Safe data transformation procedures  
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- **Schema Versioning** - Version tracking and validation
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- **Rollback Support** - Backup and recovery procedures
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## Error Handling
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- **UpgradeException** - Upgrade process failures
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- **SQLException** - Database operation errors
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- **SchemaException** - Schema validation failures
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- **DataMigrationException** - Data transformation errors