fix(snowflake): null-safe metadata compare in column-type build

chat2db-community-server/chat2db-community-plugins/chat2db-community-snowflake/src/main/java/ai/chat2db/plugin/snowflake/enums/type/SnowflakeColumnTypeEnum.java

@@ -10,6 +10,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 import static ai.chat2db.plugin.snowflake.constant.SnowflakeColumnTypeEnumConstants.*;
 public enum SnowflakeColumnTypeEnum implements IColumnBuilder {
@@ -125,8 +126,8 @@ private String buildDataType(TableColumn column, SnowflakeColumnTypeEnum type) {
         String columnType = type.columnType.getTypeName();
         if (EditStatusEnum.MODIFY.name().equals(column.getEditStatus())
                 && StringUtils.equalsIgnoreCase(column.getOldColumn().getTableName(), column.getTableName())
-                && column.getOldColumn().getColumnSize().equals(column.getColumnSize())
-                && column.getOldColumn().getDecimalDigits().equals(column.getDecimalDigits())) {
+                && Objects.equals(column.getOldColumn().getColumnSize(), column.getColumnSize())
+                && Objects.equals(column.getOldColumn().getDecimalDigits(), column.getDecimalDigits())) {
             return "";
         }
         if (Arrays.asList(BINARY, VARBINARY, VARCHAR, CHAR, STRING, TEXT).contains(type)) {
@@ -171,7 +172,10 @@ private String buildNullable(TableColumn column, SnowflakeColumnTypeEnum type) {
         if(!type.getColumnType().isSupportNullable()){
             return "";
         }
-        if (EditStatusEnum.MODIFY.name().equals(column.getEditStatus()) && !column.getNullable().equals(column.getOldColumn().getNullable())) {
+        if (EditStatusEnum.MODIFY.name().equals(column.getEditStatus())
+                && column.getNullable() != null
+                && column.getOldColumn().getNullable() != null
+                && !Objects.equals(column.getNullable(), column.getOldColumn().getNullable())) {
             if (column.getNullable()!=null && 1==column.getNullable()) {
                 return "DROP NOT NULL";
             } else {

chat2db-community-server/chat2db-community-plugins/chat2db-community-snowflake/src/test/java/ai/chat2db/plugin/snowflake/enums/type/SnowflakeColumnTypeEnumTest.java

@@ -0,0 +1,57 @@
+package ai.chat2db.plugin.snowflake.enums.type;
+
+import ai.chat2db.community.domain.api.enums.plugin.EditStatusEnum;
+import ai.chat2db.community.domain.api.model.metadata.TableColumn;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+/**
+ * Regression coverage for null {@code Integer} column metadata during MODIFY
+ * column-type generation. {@code TableColumn.columnSize}, {@code decimalDigits},
+ * and {@code nullable} are boxed {@code Integer} and can be null when the driver
+ * does not populate them; comparing them with {@code .equals()} dereferences a
+ * possibly-null value (see #1968 / {@code DBStructUtils}).
+ */
+class SnowflakeColumnTypeEnumTest {
+
+    @Test
+    void buildCreateColumnSqlToleratesNullIntegerMetadataOnModify() {
+        TableColumn oldColumn = new TableColumn();
+        oldColumn.setTableName("users");
+        // columnSize / decimalDigits / nullable intentionally left null (missing metadata)
+
+        TableColumn column = new TableColumn();
+        column.setName("amount");
+        column.setOldName("amount");
+        column.setTableName("users");
+        column.setColumnType("NUMBER");
+        column.setEditStatus(EditStatusEnum.MODIFY.name());
+        column.setOldColumn(oldColumn);
+
+        String sql = assertDoesNotThrow(() -> SnowflakeColumnTypeEnum.NUMBER.buildCreateColumnSql(column));
+        assertNotNull(sql);
+    }
+
+    @Test
+    void buildCreateColumnSqlToleratesNullNullableMetadataOnModify() {
+        TableColumn oldColumn = new TableColumn();
+        oldColumn.setTableName("users");
+        oldColumn.setNullable(1);
+
+        TableColumn column = new TableColumn();
+        column.setName("amount");
+        column.setOldName("amount");
+        column.setTableName("users");
+        column.setColumnType("NUMBER");
+        column.setEditStatus(EditStatusEnum.MODIFY.name());
+        column.setOldColumn(oldColumn);
+        // current column nullable intentionally left null (missing metadata)
+
+        String sql = assertDoesNotThrow(() -> SnowflakeColumnTypeEnum.NUMBER.buildCreateColumnSql(column));
+        assertNotNull(sql);
+        assertFalse(sql.contains("NOT NULL"), "missing nullable metadata must not change nullability");
+    }
+}