feat: expose unified table constraint inspection

Signed-off-by: minleejae <mmj9808@gmail.com>

Author: minleejae

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

@@ -11,6 +11,7 @@
 
 import java.util.Objects;
 import net.sf.jsqlparser.statement.create.table.ConstraintAttributes;
+import net.sf.jsqlparser.statement.create.table.Index;
 
 /** Changes an existing constraint using the attributes shared with CREATE and ADD. */
 public class AlterConstraintAttributes extends AlterExpression {
@@ -49,6 +50,11 @@ public void setEnforced(boolean enforced) {
         attributes.setEnforced(enforced);
     }
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder builder) {
         builder.append("ALTER CONSTRAINT ").append(getConstraintSymbol());

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

@@ -590,6 +590,56 @@ public Index getIndex() {
         return index;
     }
 
+    /**
+     * Returns the constraint kind explicitly declared or targeted by the active action. Named
+     * DROP/ALTER CONSTRAINT actions return OTHER because their SQL does not identify the kind; no
+     * catalogue lookup or inference from an inactive Index field is performed. Column actions
+     * return OTHER: inspect their ColumnOption nodes for inline constraints.
+     */
+    public Index.Kind getConstraintKind() {
+        if (operation == null) {
+            return Index.Kind.OTHER;
+        }
+        switch (operation) {
+            case DROP_PRIMARY_KEY:
+            case ALTER_PRIMARY_KEY:
+                return Index.Kind.PRIMARY_KEY;
+            case DROP_UNIQUE:
+                return Index.Kind.UNIQUE;
+            case DROP_FOREIGN_KEY:
+                return Index.Kind.FOREIGN_KEY;
+            case DROP_CHECK:
+                return Index.Kind.CHECK;
+            case ADD:
+            case ALTER:
+                if (constraintType != null && constraintSymbol != null) {
+                    Index.Kind declared = new Index().withType(constraintType).getKind();
+                    return declared.canDescribeConstraint() ? declared : Index.Kind.OTHER;
+                }
+                if (operation != AlterOperation.ADD || columnName != null
+                        || colDataTypeList != null || constraintName != null || oldIndex != null
+                        || commentText != null || columnSetNotNullList != null
+                        || columnDropNotNullList != null
+                        || columnDropDefaultList != null && !columnDropDefaultList.isEmpty()) {
+                    return Index.Kind.OTHER;
+                }
+                if (index != null) {
+                    return index.getKind() != null && index.getKind().canDescribeConstraint()
+                            ? index.getKind()
+                            : Index.Kind.OTHER;
+                }
+                if (pkColumns != null) {
+                    return Index.Kind.PRIMARY_KEY;
+                }
+                if (ukColumns != null) {
+                    return Index.Kind.UNIQUE;
+                }
+                return fkColumns != null ? Index.Kind.FOREIGN_KEY : Index.Kind.OTHER;
+            default:
+                return Index.Kind.OTHER;
+        }
+    }
+
     public void setIndex(Index index) {
         this.index = index;
     }

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

@@ -9,12 +9,19 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import net.sf.jsqlparser.statement.create.table.Index;
+
 /**
  * Internal subclass for character set and collation operations within ALTER TABLE. Handles CONVERT
  * TO CHARACTER SET, DEFAULT CHARACTER SET, CHARACTER SET, and COLLATE.
  */
 public class AlterExpressionCharset extends AlterExpression {
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder b) {
         toStringConvert(b);

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

@@ -9,13 +9,30 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+
 import net.sf.jsqlparser.statement.select.PlainSelect;
+import net.sf.jsqlparser.statement.create.table.Index;
 
 /**
  * Internal subclass for DROP operations within ALTER TABLE. Handles DROP column, DROP CONSTRAINT,
  * DROP INDEX/KEY, DROP PRIMARY KEY, DROP UNIQUE, DROP FOREIGN KEY, and DROP PARTITION.
  */
 public class AlterExpressionDrop extends AlterExpression {
+    @Override
+    public Index.Kind getConstraintKind() {
+        if (getOperation() == null) {
+            return Index.Kind.OTHER;
+        }
+        switch (getOperation()) {
+            case DROP_PRIMARY_KEY:
+            case DROP_UNIQUE:
+            case DROP_FOREIGN_KEY:
+            case DROP_CHECK:
+                return super.getConstraintKind();
+            default:
+                return Index.Kind.OTHER;
+        }
+    }
 
     @Override
     protected void appendBody(StringBuilder b) {

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

@@ -14,6 +14,7 @@
 import java.util.function.Consumer;
 import net.sf.jsqlparser.expression.Expression;
 import net.sf.jsqlparser.statement.select.OrderByElement;
+import net.sf.jsqlparser.statement.create.table.Index;
 
 /** MySQL ALTER TABLE ORDER BY, using the same mutable order elements as query ordering. */
 public class AlterExpressionOrderBy extends AlterExpression {
@@ -27,6 +28,11 @@ public List<OrderByElement> getOrderByElements() {
         return orderByElements;
     }
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder builder) {
         appendOrderBy(builder, builder::append);

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

@@ -21,6 +21,7 @@
 import net.sf.jsqlparser.statement.create.table.PartitionDefinition;
 import net.sf.jsqlparser.statement.create.table.TablePartitioning;
 import net.sf.jsqlparser.statement.select.PlainSelect;
+import net.sf.jsqlparser.statement.create.table.Index;
 
 /**
  * Structured model for partition operations within {@code ALTER TABLE}.
@@ -292,6 +293,11 @@ public AlterExpressionPartition addPartitionDefinitions(
         return withPartitionDefinitions(collection);
     }
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder b) {
         appendBody(b, b::append);

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

@@ -44,6 +44,11 @@ public void setBucketCount(Expression bucketCount) {
         this.bucketCount = bucketCount;
     }
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.PRIMARY_KEY;
+    }
+
     @Override
     protected void appendBody(StringBuilder builder) {
         appendDefinition(builder, expression -> builder.append(expression));

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

@@ -9,12 +9,19 @@
  */
 package net.sf.jsqlparser.statement.alter;
 
+import net.sf.jsqlparser.statement.create.table.Index;
+
 /**
  * Internal subclass for RENAME operations within ALTER TABLE. Handles RENAME COLUMN, RENAME TO
  * (table), RENAME INDEX/KEY/CONSTRAINT.
  */
 public class AlterExpressionRename extends AlterExpression {
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder b) {
         switch (getOperation()) {

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

@@ -10,6 +10,7 @@
 package net.sf.jsqlparser.statement.alter;
 
 import net.sf.jsqlparser.statement.create.table.TableOption;
+import net.sf.jsqlparser.statement.create.table.Index;
 
 /**
  * Internal subclass for table-level option operations within ALTER TABLE. Handles ENGINE,
@@ -128,6 +129,11 @@ public void setUseEqual(boolean useEqual) {
         super.setUseEqual(useEqual);
     }
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder b) {
         if (structuredTableOption != null) {

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

@@ -13,6 +13,7 @@
 import java.util.function.Consumer;
 import net.sf.jsqlparser.expression.Expression;
 import net.sf.jsqlparser.statement.create.table.ForeignDataOption;
+import net.sf.jsqlparser.statement.create.table.Index;
 
 /** Foreign table OPTIONS, optionally applied to one column. */
 public class AlterForeignDataOptions extends AlterExpression {
@@ -39,6 +40,11 @@ public StringBuilder appendTo(StringBuilder builder, Consumer<Expression> expres
         return builder;
     }
 
+    @Override
+    public Index.Kind getConstraintKind() {
+        return Index.Kind.OTHER;
+    }
+
     @Override
     protected void appendBody(StringBuilder builder) {
         appendTo(builder, builder::append);