feat: ALTER TABLE DDL generation for all database plugins

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Structure tab: modify existing tables (add, modify, drop columns, indexes, foreign keys, primary keys)
+
 ## [0.33.0] - 2026-04-19
 
 ### Added

Packages/TableProCore/Sources/TableProPluginKit/DriverPlugin.swift

@@ -53,6 +53,16 @@ public protocol DriverPlugin: TableProPlugin {
     static var isDownloadable: Bool { get }
     static var postConnectActions: [PostConnectAction] { get }
     static var parameterStyle: ParameterStyle { get }
+    static var supportsDropDatabase: Bool { get }
+
+    // Schema editing granularity
+    static var supportsAddColumn: Bool { get }
+    static var supportsModifyColumn: Bool { get }
+    static var supportsDropColumn: Bool { get }
+    static var supportsRenameColumn: Bool { get }
+    static var supportsAddIndex: Bool { get }
+    static var supportsDropIndex: Bool { get }
+    static var supportsModifyPrimaryKey: Bool { get }
 }
 
 public extension DriverPlugin {
@@ -113,4 +123,14 @@ public extension DriverPlugin {
     static var parameterStyle: ParameterStyle { .questionMark }
     static var isDownloadable: Bool { false }
     static var postConnectActions: [PostConnectAction] { [] }
+    static var supportsDropDatabase: Bool { false }
+
+    // Schema editing granularity
+    static var supportsAddColumn: Bool { true }
+    static var supportsModifyColumn: Bool { true }
+    static var supportsDropColumn: Bool { true }
+    static var supportsRenameColumn: Bool { false }
+    static var supportsAddIndex: Bool { true }
+    static var supportsDropIndex: Bool { true }
+    static var supportsModifyPrimaryKey: Bool { true }
 }

Plugins/CassandraDriverPlugin/CassandraPlugin.swift

@@ -1269,6 +1269,21 @@ internal final class CassandraPluginDriver: PluginDatabaseDriver, @unchecked Sen
         try await switchDatabase(to: schema)
     }
 
+    // MARK: - ALTER TABLE DDL
+
+    func generateAddColumnSQL(table: String, column: PluginColumnDefinition) -> String? {
+        "ALTER TABLE \(qualifiedTableName(table)) ADD \(quoteIdentifier(column.name)) \(column.dataType)"
+    }
+
+    func generateDropColumnSQL(table: String, columnName: String) -> String? {
+        "ALTER TABLE \(qualifiedTableName(table)) DROP \(quoteIdentifier(columnName))"
+    }
+
+    private func qualifiedTableName(_ table: String) -> String {
+        let ks = resolveKeyspace(nil)
+        return "\(quoteIdentifier(ks)).\(quoteIdentifier(table))"
+    }
+
     // MARK: - Private Helpers
 
     private func resolveKeyspace(_ schema: String?) -> String {

Plugins/ClickHouseDriverPlugin/ClickHousePlugin.swift

@@ -1320,6 +1320,39 @@ final class ClickHousePluginDriver: PluginDatabaseDriver, @unchecked Sendable {
         return "'\(escapeStringLiteral(value))'"
     }
 
+    // MARK: - ALTER TABLE DDL
+
+    func generateAddColumnSQL(table: String, column: PluginColumnDefinition) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) ADD COLUMN \(clickhouseColumnDefinition(column))"
+    }
+
+    func generateModifyColumnSQL(table: String, oldColumn: PluginColumnDefinition, newColumn: PluginColumnDefinition) -> String? {
+        let tableName = quoteIdentifier(table)
+        var stmts: [String] = []
+        if oldColumn.name != newColumn.name {
+            stmts.append("ALTER TABLE \(tableName) RENAME COLUMN \(quoteIdentifier(oldColumn.name)) TO \(quoteIdentifier(newColumn.name))")
+        }
+        if oldColumn.dataType != newColumn.dataType || oldColumn.isNullable != newColumn.isNullable
+            || oldColumn.defaultValue != newColumn.defaultValue || oldColumn.comment != newColumn.comment {
+            stmts.append("ALTER TABLE \(tableName) MODIFY COLUMN \(clickhouseColumnDefinition(newColumn))")
+        }
+        return stmts.isEmpty ? nil : stmts.joined(separator: ";\n")
+    }
+
+    func generateDropColumnSQL(table: String, columnName: String) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) DROP COLUMN \(quoteIdentifier(columnName))"
+    }
+
+    func generateAddIndexSQL(table: String, index: PluginIndexDefinition) -> String? {
+        let cols = index.columns.map { quoteIdentifier($0) }.joined(separator: ", ")
+        let indexType = index.indexType ?? "minmax"
+        return "ALTER TABLE \(quoteIdentifier(table)) ADD INDEX \(quoteIdentifier(index.name)) (\(cols)) TYPE \(indexType) GRANULARITY 1"
+    }
+
+    func generateDropIndexSQL(table: String, indexName: String) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) DROP INDEX \(quoteIdentifier(indexName))"
+    }
+
     // MARK: - TLS Delegate
 
     private class InsecureTLSDelegate: NSObject, URLSessionDelegate {

Plugins/DuckDBDriverPlugin/DuckDBPlugin.swift

@@ -1315,6 +1315,82 @@ final class DuckDBPluginDriver: PluginDatabaseDriver, @unchecked Sendable {
         return def
     }
 
+    private func qualifiedTableName(_ table: String) -> String {
+        "\(quoteIdentifier(_currentSchema)).\(quoteIdentifier(table))"
+    }
+
+    // MARK: - ALTER TABLE DDL
+
+    func generateAddColumnSQL(table: String, column: PluginColumnDefinition) -> String? {
+        let qt = qualifiedTableName(table)
+        let colDef = duckdbColumnDefinition(column, inlinePK: false)
+        return "ALTER TABLE \(qt) ADD COLUMN \(colDef)"
+    }
+
+    func generateModifyColumnSQL(table: String, oldColumn: PluginColumnDefinition, newColumn: PluginColumnDefinition) -> String? {
+        let qt = qualifiedTableName(table)
+        var stmts: [String] = []
+
+        if oldColumn.name != newColumn.name {
+            stmts.append("ALTER TABLE \(qt) RENAME COLUMN \(quoteIdentifier(oldColumn.name)) TO \(quoteIdentifier(newColumn.name))")
+        }
+
+        let colName = quoteIdentifier(newColumn.name)
+
+        if oldColumn.dataType.uppercased() != newColumn.dataType.uppercased() {
+            stmts.append("ALTER TABLE \(qt) ALTER COLUMN \(colName) TYPE \(newColumn.dataType)")
+        }
+
+        if oldColumn.isNullable != newColumn.isNullable {
+            let clause = newColumn.isNullable ? "DROP NOT NULL" : "SET NOT NULL"
+            stmts.append("ALTER TABLE \(qt) ALTER COLUMN \(colName) \(clause)")
+        }
+
+        if oldColumn.defaultValue != newColumn.defaultValue {
+            if let defaultValue = newColumn.defaultValue {
+                stmts.append("ALTER TABLE \(qt) ALTER COLUMN \(colName) SET DEFAULT \(duckdbDefaultValue(defaultValue))")
+            } else {
+                stmts.append("ALTER TABLE \(qt) ALTER COLUMN \(colName) DROP DEFAULT")
+            }
+        }
+
+        return stmts.isEmpty ? nil : stmts.joined(separator: ";\n")
+    }
+
+    func generateDropColumnSQL(table: String, columnName: String) -> String? {
+        "ALTER TABLE \(qualifiedTableName(table)) DROP COLUMN \(quoteIdentifier(columnName))"
+    }
+
+    func generateAddIndexSQL(table: String, index: PluginIndexDefinition) -> String? {
+        duckdbIndexDefinition(index, qualifiedTable: qualifiedTableName(table))
+    }
+
+    func generateDropIndexSQL(table: String, indexName: String) -> String? {
+        "DROP INDEX \(quoteIdentifier(indexName))"
+    }
+
+    func generateAddForeignKeySQL(table: String, fk: PluginForeignKeyDefinition) -> String? {
+        "ALTER TABLE \(qualifiedTableName(table)) ADD \(duckdbForeignKeyDefinition(fk))"
+    }
+
+    func generateDropForeignKeySQL(table: String, constraintName: String) -> String? {
+        "ALTER TABLE \(qualifiedTableName(table)) DROP CONSTRAINT \(quoteIdentifier(constraintName))"
+    }
+
+    func generateModifyPrimaryKeySQL(table: String, oldColumns: [String], newColumns: [String], constraintName: String?) -> [String]? {
+        let qt = qualifiedTableName(table)
+        var stmts: [String] = []
+        if !oldColumns.isEmpty {
+            let name = constraintName.map { quoteIdentifier($0) } ?? "/* unknown constraint */"
+            stmts.append("ALTER TABLE \(qt) DROP CONSTRAINT \(name)")
+        }
+        if !newColumns.isEmpty {
+            let cols = newColumns.map { quoteIdentifier($0) }.joined(separator: ", ")
+            stmts.append("ALTER TABLE \(qt) ADD PRIMARY KEY (\(cols))")
+        }
+        return stmts.isEmpty ? nil : stmts
+    }
+
     private static let indexColumnsRegex = try? NSRegularExpression(
         pattern: #"ON\s+(?:(?:"[^"]*"|[^\s(]+)\s*\.\s*)*(?:"[^"]*"|[^\s(]+)\s*\(([^)]+)\)"#,
         options: .caseInsensitive

Plugins/MSSQLDriverPlugin/MSSQLPlugin.swift

@@ -1707,6 +1707,90 @@ final class MSSQLPluginDriver: PluginDatabaseDriver, @unchecked Sendable {
         return def
     }
 
+    // MARK: - ALTER TABLE DDL
+
+    private func mssqlQualifiedTable(_ table: String) -> String {
+        "\(quoteIdentifier(_currentSchema)).\(quoteIdentifier(table))"
+    }
+
+    func generateAddColumnSQL(table: String, column: PluginColumnDefinition) -> String? {
+        "ALTER TABLE \(mssqlQualifiedTable(table)) ADD \(mssqlColumnDefinition(column, inlinePK: false))"
+    }
+
+    func generateModifyColumnSQL(table: String, oldColumn: PluginColumnDefinition, newColumn: PluginColumnDefinition) -> String? {
+        let qt = mssqlQualifiedTable(table)
+        var stmts: [String] = []
+        let needsTypeChange = oldColumn.dataType != newColumn.dataType || oldColumn.isNullable != newColumn.isNullable
+        let defaultChanged = oldColumn.defaultValue != newColumn.defaultValue
+
+        // Rename column first so subsequent statements reference the correct name
+        if oldColumn.name != newColumn.name {
+            let escapedPath = "\(escapeStringLiteral(_currentSchema)).\(escapeStringLiteral(table)).\(escapeStringLiteral(oldColumn.name))"
+            stmts.append("EXEC sp_rename '\(escapedPath)', '\(escapeStringLiteral(newColumn.name))', 'COLUMN'")
+        }
+
+        let colName = quoteIdentifier(newColumn.name)
+
+        // Drop existing default constraint before ALTER COLUMN or default change
+        if (defaultChanged || needsTypeChange) && oldColumn.defaultValue != nil {
+            let objectId = escapeStringLiteral("\(_currentSchema).\(table)")
+            stmts.append("""
+                DECLARE @dfName NVARCHAR(256); \
+                SELECT @dfName = dc.name FROM sys.default_constraints dc \
+                JOIN sys.columns c ON dc.parent_column_id = c.column_id AND dc.parent_object_id = c.object_id \
+                WHERE c.name = '\(escapeStringLiteral(newColumn.name))' \
+                AND dc.parent_object_id = OBJECT_ID('\(objectId)'); \
+                IF @dfName IS NOT NULL EXEC('ALTER TABLE \(qt) DROP CONSTRAINT [' + @dfName + ']')
+                """)
+        }
+
+        if needsTypeChange {
+            let nullable = newColumn.isNullable ? "NULL" : "NOT NULL"
+            stmts.append("ALTER TABLE \(qt) ALTER COLUMN \(colName) \(newColumn.dataType) \(nullable)")
+        }
+
+        if defaultChanged, let defaultValue = newColumn.defaultValue {
+            stmts.append("ALTER TABLE \(qt) ADD DEFAULT \(mssqlDefaultValue(defaultValue)) FOR \(colName)")
+        }
+
+        return stmts.isEmpty ? nil : stmts.joined(separator: ";\n")
+    }
+
+    func generateDropColumnSQL(table: String, columnName: String) -> String? {
+        "ALTER TABLE \(mssqlQualifiedTable(table)) DROP COLUMN \(quoteIdentifier(columnName))"
+    }
+
+    func generateAddIndexSQL(table: String, index: PluginIndexDefinition) -> String? {
+        mssqlIndexDefinition(index, qualifiedTable: mssqlQualifiedTable(table))
+    }
+
+    func generateDropIndexSQL(table: String, indexName: String) -> String? {
+        "DROP INDEX \(quoteIdentifier(indexName)) ON \(mssqlQualifiedTable(table))"
+    }
+
+    func generateAddForeignKeySQL(table: String, fk: PluginForeignKeyDefinition) -> String? {
+        "ALTER TABLE \(mssqlQualifiedTable(table)) ADD \(mssqlForeignKeyDefinition(fk))"
+    }
+
+    func generateDropForeignKeySQL(table: String, constraintName: String) -> String? {
+        "ALTER TABLE \(mssqlQualifiedTable(table)) DROP CONSTRAINT \(quoteIdentifier(constraintName))"
+    }
+
+    func generateModifyPrimaryKeySQL(table: String, oldColumns: [String], newColumns: [String], constraintName: String?) -> [String]? {
+        let qt = mssqlQualifiedTable(table)
+        var stmts: [String] = []
+        if !oldColumns.isEmpty {
+            let name = constraintName.map { quoteIdentifier($0) } ?? "/* unknown constraint */"
+            stmts.append("ALTER TABLE \(qt) DROP CONSTRAINT \(name)")
+        }
+        if !newColumns.isEmpty {
+            let cols = newColumns.map { quoteIdentifier($0) }.joined(separator: ", ")
+            let pkName = constraintName.map { quoteIdentifier($0) } ?? quoteIdentifier("PK_\(table)")
+            stmts.append("ALTER TABLE \(qt) ADD CONSTRAINT \(pkName) PRIMARY KEY (\(cols))")
+        }
+        return stmts.isEmpty ? nil : stmts
+    }
+
     private func stripMSSQLOffsetFetch(from query: String) -> String {
         let ns = query.uppercased() as NSString
         let len = ns.length

Plugins/MySQLDriverPlugin/MySQLPluginDriver.swift

@@ -871,6 +871,53 @@ final class MySQLPluginDriver: PluginDatabaseDriver, @unchecked Sendable {
         buildForeignKeyDefinitionSQL(fk)
     }
 
+    // MARK: - ALTER TABLE DDL
+
+    func generateAddColumnSQL(table: String, column: PluginColumnDefinition) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) ADD COLUMN \(buildColumnDefinitionSQL(column))"
+    }
+
+    func generateModifyColumnSQL(table: String, oldColumn: PluginColumnDefinition, newColumn: PluginColumnDefinition) -> String? {
+        let tableName = quoteIdentifier(table)
+        if oldColumn.name != newColumn.name {
+            return "ALTER TABLE \(tableName) CHANGE COLUMN \(quoteIdentifier(oldColumn.name)) \(buildColumnDefinitionSQL(newColumn))"
+        }
+        return "ALTER TABLE \(tableName) MODIFY COLUMN \(buildColumnDefinitionSQL(newColumn))"
+    }
+
+    func generateDropColumnSQL(table: String, columnName: String) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) DROP COLUMN \(quoteIdentifier(columnName))"
+    }
+
+    func generateAddIndexSQL(table: String, index: PluginIndexDefinition) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) ADD \(buildIndexDefinitionSQL(index))"
+    }
+
+    func generateDropIndexSQL(table: String, indexName: String) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) DROP INDEX \(quoteIdentifier(indexName))"
+    }
+
+    func generateAddForeignKeySQL(table: String, fk: PluginForeignKeyDefinition) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) ADD \(buildForeignKeyDefinitionSQL(fk))"
+    }
+
+    func generateDropForeignKeySQL(table: String, constraintName: String) -> String? {
+        "ALTER TABLE \(quoteIdentifier(table)) DROP FOREIGN KEY \(quoteIdentifier(constraintName))"
+    }
+
+    func generateModifyPrimaryKeySQL(table: String, oldColumns: [String], newColumns: [String], constraintName: String?) -> [String]? {
+        let tableName = quoteIdentifier(table)
+        var stmts: [String] = []
+        if !oldColumns.isEmpty {
+            stmts.append("ALTER TABLE \(tableName) DROP PRIMARY KEY")
+        }
+        if !newColumns.isEmpty {
+            let cols = newColumns.map { quoteIdentifier($0) }.joined(separator: ", ")
+            stmts.append("ALTER TABLE \(tableName) ADD PRIMARY KEY (\(cols))")
+        }
+        return stmts.isEmpty ? nil : stmts
+    }
+
     // MARK: - Column Reorder DDL
 
     func generateMoveColumnSQL(table: String, column: PluginColumnDefinition, afterColumn: String?) -> String? {