branch-3.0: [improvement](jdbc catalog) Optimize the acquisition of indentity type in SQLServer #51285

docker/thirdparties/docker-compose/sqlserver/init/03-create-table.sql

@@ -271,4 +271,9 @@ CREATE TABLE dbo.extreme_test_multi_block
     IPv4_Nullable    VARCHAR(15) NULL,
     IPv6_Col         VARCHAR(39) NOT NULL,  -- e.g., 'FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF'
     IPv6_Nullable    VARCHAR(39) NULL
-);
+);
+
+CREATE TABLE dbo.test_identity_decimal (
+	id decimal(18,0) IDENTITY(1,1),
+	col int
+);

docker/thirdparties/docker-compose/sqlserver/init/04-insert.sql

@@ -121,3 +121,5 @@ insert into dbo.extreme_test_multi_block select * from dbo.extreme_test_multi_bl
 insert into dbo.extreme_test_multi_block select * from dbo.extreme_test_multi_block;
 insert into dbo.extreme_test_multi_block select * from dbo.extreme_test_multi_block;
 insert into dbo.extreme_test_multi_block select * from dbo.extreme_test;
+
+INSERT INTO dbo.test_identity_decimal(col) select 1;

fe/fe-core/src/main/java/org/apache/doris/datasource/jdbc/client/JdbcSQLServerClient.java

@@ -32,7 +32,14 @@ protected Type jdbcTypeToDoris(JdbcFieldSchema fieldSchema) {
         String originSqlserverType = fieldSchema.getDataTypeName().orElse("unknown");
         // For sqlserver IDENTITY type, such as 'INT IDENTITY'
         // originSqlserverType is "int identity", so we only get "int".
+        // For types with parameters like 'decimal(18,0) IDENTITY(1,1)', we need to extract the base type
         String sqlserverType = originSqlserverType.split(" ")[0];
+
+        // Handle types with parentheses like decimal(18,0), varchar(50), etc.
+        if (sqlserverType.contains("(")) {
+            sqlserverType = sqlserverType.substring(0, sqlserverType.indexOf("("));
+        }
+
         switch (sqlserverType) {
             case "bit":
                 return Type.BOOLEAN;
@@ -55,7 +62,7 @@ protected Type jdbcTypeToDoris(JdbcFieldSchema fieldSchema) {
             case "numeric": {
                 int precision = fieldSchema.getColumnSize().orElse(0);
                 int scale = fieldSchema.getDecimalDigits().orElse(0);
-                return ScalarType.createDecimalV3Type(precision, scale);
+                return createDecimalOrStringType(precision, scale);
             }
             case "date":
                 return ScalarType.createDateV2Type();

regression-test/data/external_table_p0/jdbc/test_sqlserver_jdbc_catalog.out

@@ -130,6 +130,9 @@ timestamp_col	text	Yes	true	\N
 1	doris	18	0	1	1	123.123	123.123	123.123	12345678901234567890123456789012345678	12345678901234567890123456789012345678	1234567890123456789012345678.0123456789	1234567890123456789012345678.0123456789	Make Doris Great!   	Make Doris Great!	Make Doris Great!	Make Doris Great!   	Make Doris Great!	Make Doris Great!	2023-01-17	16:49:05.123	2023-01-17T16:49:05	2023-01-17T16:49:05.123456	2023-01-17T16:49	2023-01-17 16:49:05 +08:00	Make Doris Great!	Make Doris Great!	922337203685477.5807	214748.3647	false
 2	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N	\N
 
+-- !identity_decimal --
+1	1
+
 -- !sql --
 db_accessadmin
 db_backupoperator

regression-test/suites/external_table_p0/jdbc/test_sqlserver_jdbc_catalog.groovy

@@ -83,6 +83,8 @@ suite("test_sqlserver_jdbc_catalog", "p0,external,sqlserver,external_docker,exte
 
         order_qt_all_types_tvf """ select * from query('catalog' = '${catalog_name}', 'query' = 'select * from all_type;') order by 1"""
 
+        order_qt_identity_decimal """ select * from test_identity_decimal order by id; """
+
         sql """ drop catalog if exists ${catalog_name} """
 
         sql """ create catalog if not exists ${catalog_name} properties(