ALTER TABLE ALTER COLUMN SET DATA TYPE is a standard syntax

h2/src/docsrc/help/help.csv

@@ -359,6 +359,7 @@ ALTER TABLE [ IF EXISTS ] tableName ALTER COLUMN columnName
     | { SET ON UPDATE expression }
     | { SET NOT NULL }
     | { DROP NOT NULL } | { SET NULL }
+    | { SET DATA TYPE dataType }
     | { SET { VISIBLE | INVISIBLE } }
     | { DROP ON UPDATE } }
 ","
@@ -386,6 +387,8 @@ SET NOT NULL sets a column to not allow NULL. Rows may not contains NULL in this
 
 DROP NOT NULL and SET NULL set a column to allow NULL. The row may not be part of a primary key.
 
+SET DATA TYPE changes the data type of a column.
+
 SET INVISIBLE makes the column hidden, i.e. it will not appear in SELECT * results.
 SET VISIBLE has the reverse effect.
 

h2/src/main/org/h2/command/Parser.java

@@ -7277,14 +7277,11 @@ public class Parser {
                 return command;
             } else if (readIf("TYPE")) {
                 // PostgreSQL compatibility
-                return parseAlterTableAlterColumnType(schema, tableName,
-                        columnName, ifTableExists);
+                return parseAlterTableAlterColumnDataType(schema, tableName, columnName, ifTableExists);
             } else if (readIf("SET")) {
                 if (readIf("DATA")) {
-                    // Derby compatibility
                     read("TYPE");
-                    return parseAlterTableAlterColumnType(schema, tableName, columnName,
-                            ifTableExists);
+                    return parseAlterTableAlterColumnDataType(schema, tableName, columnName, ifTableExists);
                 }
                 AlterTableAlterColumn command = new AlterTableAlterColumn(
                         session, schema);
@@ -7341,8 +7338,7 @@ public class Parser {
                 command.setSelectivity(readExpression());
                 return command;
             } else {
-                return parseAlterTableAlterColumnType(schema, tableName,
-                        columnName, ifTableExists);
+                return parseAlterTableAlterColumnType(schema, tableName, columnName, ifTableExists);
             }
         }
         throw getSyntaxError();
@@ -7374,8 +7370,48 @@ public class Parser {
         Column oldColumn = columnIfTableExists(schema, tableName, columnName, ifTableExists);
         Column newColumn = parseColumnForTable(columnName,
                 oldColumn == null ? true : oldColumn.isNullable(), true);
-        AlterTableAlterColumn command = new AlterTableAlterColumn(session,
-                schema);
+        if (readIf(CHECK)) {
+            Expression expr = readExpression();
+            newColumn.addCheckConstraint(session, expr);
+        }
+        AlterTableAlterColumn command = new AlterTableAlterColumn(session, schema);
+        command.setTableName(tableName);
+        command.setIfTableExists(ifTableExists);
+        command.setType(CommandInterface.ALTER_TABLE_ALTER_COLUMN_CHANGE_TYPE);
+        command.setOldColumn(oldColumn);
+        command.setNewColumn(newColumn);
+        return command;
+    }
+
+    private AlterTableAlterColumn parseAlterTableAlterColumnDataType(Schema schema,
+            String tableName, String columnName, boolean ifTableExists) {
+        Column oldColumn = columnIfTableExists(schema, tableName, columnName, ifTableExists);
+        Column newColumn = parseColumnWithType(columnName, true);
+        if (oldColumn != null) {
+            if (!oldColumn.isNullable()) {
+                newColumn.setNullable(false);
+            }
+            if (!oldColumn.getVisible()) {
+                newColumn.setVisible(false);
+            }
+            Expression e = oldColumn.getDefaultExpression();
+            if (e != null) {
+                newColumn.setDefaultExpression(session, e);
+            }
+            e = oldColumn.getOnUpdateExpression();
+            if (e != null) {
+                newColumn.setOnUpdateExpression(session, e);
+            }
+            e = oldColumn.getCheckConstraint(session, columnName);
+            if (e != null) {
+                newColumn.addCheckConstraint(session, e);
+            }
+            String c = oldColumn.getComment();
+            if (c != null) {
+                newColumn.setComment(c);
+            }
+        }
+        AlterTableAlterColumn command = new AlterTableAlterColumn(session, schema);
         command.setTableName(tableName);
         command.setIfTableExists(ifTableExists);
         command.setType(CommandInterface.ALTER_TABLE_ALTER_COLUMN_CHANGE_TYPE);

h2/src/test/org/h2/test/scripts/ddl/alterTableAlterColumn.sql

@@ -47,5 +47,24 @@ ALTER TABLE TEST ALTER COLUMN T SET NULL;
 SELECT COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'T';
 >> INT
 
+-- SET DATA TYPE
+ALTER TABLE TEST ALTER COLUMN T SET DATA TYPE BIGINT;
+> ok
+
+SELECT COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'T';
+>> BIGINT
+
+ALTER TABLE TEST ALTER COLUMN T INT INVISIBLE DEFAULT 1 ON UPDATE 2 NOT NULL COMMENT 'C' CHECK T < 100;
+> ok
+
+SELECT COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'T';
+>> INT INVISIBLE DEFAULT 1 ON UPDATE 2 NOT NULL COMMENT 'C' CHECK (T < 100)
+
+ALTER TABLE TEST ALTER COLUMN T SET DATA TYPE BIGINT;
+> ok
+
+SELECT COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'T';
+>> BIGINT INVISIBLE DEFAULT 1 ON UPDATE 2 NOT NULL COMMENT 'C' CHECK (T < 100)
+
 DROP TABLE TEST;
 > ok