Added support for 'ALTER TABLE CHANGE COLUMN' (#741)

* Added support for 'ALTER TABLE CHANGE COLUMN oldName newName columnDefinition'. Please see https://dev.mysql.com/doc/refman/8.0/en/alter-table.html for reference.

* Returned import ordering to avoid conflicts

* Improved the tests somewhat

Now also test the getOptionalSpecifier() for both cases (null and not-null)

* Expanded tests for ALTER TABLE ... CHANGE

Author: Gikkman

src/main/java/net/sf/jsqlparser/statement/alter/AlterExpression.java

@@ -37,7 +37,9 @@
 public class AlterExpression {
 
     private AlterOperation operation;
+    private String optionalSpecifier;
     private String columnName;
+    private String columnOldName;
     //private ColDataType dataType;
 
     private List<ColumnDataType> colDataTypeList;
@@ -66,6 +68,14 @@ public void setOperation(AlterOperation operation) {
         this.operation = operation;
     }
 
+    public String getOptionalSpecifier() {
+        return optionalSpecifier;
+    }
+
+    public void setOptionalSpecifier(String optionalSpecifier) {
+        this.optionalSpecifier = optionalSpecifier;
+    }
+
     public boolean isOnDeleteCascade() {
         return onDeleteCascade;
     }
@@ -137,6 +147,14 @@ public void setColumnName(String columnName) {
         this.columnName = columnName;
     }
 
+    public String getColOldName() {
+        return columnOldName;
+    }
+
+    public void setColOldName(String columnOldName) {
+        this.columnOldName = columnOldName;
+    }
+
     public String getConstraintName() {
         return this.constraintName;
     }
@@ -214,7 +232,12 @@ public String toString() {
         if (columnName != null) {
             b.append("COLUMN ").append(columnName);
         } else if (getColDataTypeList() != null) {
-            if (colDataTypeList.size() > 1) {
+            if(operation == AlterOperation.CHANGE) {
+                if(optionalSpecifier != null) {
+                    b.append(optionalSpecifier).append(" ");
+                }
+                b.append(columnOldName).append(" ");
+            } else if (colDataTypeList.size() > 1) {
                 b.append("(");
             } else {
                 b.append("COLUMN ");

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -158,6 +158,7 @@ TOKEN: /* SQL Keywords. prefixed with K_ to avoid name clashes */
 |   <K_CASE:"CASE">
 |   <K_CAST:"CAST">
 |   <K_CHARACTER:"CHARACTER">
+|   <K_CHANGE:"CHANGE">
 |   <K_CHECK:"CHECK">
 |   <K_CHAR:"CHAR">
 |   <K_COLUMN:"COLUMN">
@@ -3866,6 +3867,22 @@ AlterExpression AlterExpression():
         )
     )
     |
+    (<K_CHANGE>
+      {
+        alterExp.setOperation(AlterOperation.CHANGE);
+      }
+      (
+        <K_COLUMN> { alterExp.setOptionalSpecifier("COLUMN"); } | {}
+      )
+      (
+        (tk=<S_IDENTIFIER> | tk=<S_QUOTED_IDENTIFIER>)
+        alterExpressionColumnDataType = AlterExpressionColumnDataType() {
+            alterExp.setColOldName(tk.image);
+            alterExp.addColDataType(alterExpressionColumnDataType);
+        }
+      )
+    )
+    |
     (<K_DROP>
       {
             alterExp.setOperation(AlterOperation.DROP);

src/test/java/net/sf/jsqlparser/statement/alter/AlterTest.java

@@ -262,6 +262,34 @@ public void testAlterTableAlterColumn() throws JSQLParserException {
       assertSqlCanBeParsedAndDeparsed("ALTER TABLE table_name ALTER COLUMN column_name_1 TYPE TIMESTAMP, ALTER COLUMN column_name_2 TYPE BOOLEAN");
     }
 
+    @Test
+    public void testAlterTableChangeColumn1() throws JSQLParserException {
+        Statement stmt = CCJSqlParserUtil.parse("ALTER TABLE tb_test CHANGE COLUMN c1 c2 INT (10)");
+        Alter alter = (Alter) stmt;
+        assertEquals(AlterOperation.CHANGE, alter.getAlterExpressions().get(0).getOperation());
+        assertEquals("c1", alter.getAlterExpressions().get(0).getColOldName());
+        assertEquals("COLUMN", alter.getAlterExpressions().get(0).getOptionalSpecifier());
+    }
+
+    @Test
+    public void testAlterTableChangeColumn2() throws JSQLParserException {
+        Statement stmt = CCJSqlParserUtil.parse("ALTER TABLE tb_test CHANGE c1 c2 INT (10)");
+        Alter alter = (Alter) stmt;
+        assertEquals(AlterOperation.CHANGE, alter.getAlterExpressions().get(0).getOperation());
+        assertEquals("c1", alter.getAlterExpressions().get(0).getColOldName());
+        assertNull(alter.getAlterExpressions().get(0).getOptionalSpecifier());
+    }
+
+    @Test
+    public void testAlterTableChangeColumn3() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("ALTER TABLE tb_test CHANGE COLUMN c1 c2 INT (10)");
+    }
+
+    @Test
+    public void testAlterTableChangeColumn4() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("ALTER TABLE tb_test CHANGE c1 c2 INT (10)");
+    }
+
     @Test
     public void testAlterTableAddColumnWithZone() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("ALTER TABLE mytable ADD COLUMN col1 timestamp with time zone");