diff --git a/testdata/sqllogictests_bigquery/validation.slt b/testdata/sqllogictests_bigquery/validation.slt
index 8dc62acab..e36a3954e 100644
--- a/testdata/sqllogictests_bigquery/validation.slt
+++ b/testdata/sqllogictests_bigquery/validation.slt
@@ -1,5 +1,25 @@
 # Validation tests for big query external database and external tables
 
+# External database validation
+
+# Validation test with wrong key
+statement error
+CREATE EXTERNAL DATABASE wrong_key
+    FROM bigquery OPTIONS (
+        service_account_key = '{"random": "key"}',
+        project_id = '${GCP_PROJECT_ID}',
+    );
+
+# Validation test with non-existent project
+statement error
+CREATE EXTERNAL DATABASE non_existant_project
+    FROM bigquery OPTIONS (
+        service_account_key = '${GCP_SERVICE_ACCOUNT_KEY}',
+        project_id = '${GCP_PROJECT_ID}-bad-project',
+    );
+
+# External table validation
+
 # Validation test with empty key
 statement error
 CREATE EXTERNAL TABLE empty_key
diff --git a/testdata/sqllogictests_mysql/validation.slt b/testdata/sqllogictests_mysql/validation.slt
index ce37c36b0..21fa11b54 100644
--- a/testdata/sqllogictests_mysql/validation.slt
+++ b/testdata/sqllogictests_mysql/validation.slt
@@ -1,5 +1,32 @@
 # Validation tests for mysql external database and external tables
 
+# External database validation
+
+# Validation test error with the wrong password
+statement error
+CREATE EXTERNAL DATABASE wrong_password
+    FROM mysql
+    OPTIONS (
+        connection_string = 'mysql://root:wrong_password@127.0.0.1:3307/glaredb_test',
+    );
+
+statement error
+CREATE EXTERNAL DATABASE non_existant_user
+    FROM mysql
+    OPTIONS (
+        connection_string = 'mysql://missing@127.0.0.1:3307/glaredb_test',
+    );
+
+# Validation test error with the wrong host
+statement error
+CREATE EXTERNAL DATABASE wrong_host
+    FROM mysql
+    OPTIONS (
+        connection_string = 'mysql://root@non-existant:3307/glaredb_test',
+    );
+
+# External table validation
+
 # Validation test error with the wrong password
 statement error
 CREATE EXTERNAL TABLE wrong_password
diff --git a/testdata/sqllogictests_postgres/validation.slt b/testdata/sqllogictests_postgres/validation.slt
index 405e831fd..a9e24f532 100644
--- a/testdata/sqllogictests_postgres/validation.slt
+++ b/testdata/sqllogictests_postgres/validation.slt
@@ -1,5 +1,32 @@
 # Validation tests for postgres external database and external tables
 
+# External database validation
+
+# Validation test error with the wrong password
+statement error
+CREATE EXTERNAL DATABASE wrong_password
+	FROM postgres
+	OPTIONS (
+		connection_string = 'host=localhost port=5432 user=glaredb password=wrong-password dbname=glaredb_test sslmode=disable',
+	);
+
+statement error
+CREATE EXTERNAL DATABASE non_existant_user
+	FROM postgres
+	OPTIONS (
+		connection_string = 'host=localhost port=5432 user=missing password=password dbname=glaredb_test sslmode=disable',
+	);
+
+# Validation test error with the wrong host
+statement error
+CREATE EXTERNAL DATABASE wrong_host
+	FROM postgres
+	OPTIONS (
+		connection_string = 'host=non-existant port=5432 user=glaredb password=password dbname=glaredb_test sslmode=disable',
+	);
+
+# External table validation
+
 # Validation test error with the wrong password
 statement error
 CREATE EXTERNAL TABLE wrong_password
@@ -39,7 +66,7 @@ CREATE EXTERNAL TABLE missing_table
 		table = 'missing_table'
 	);
 
-# Validation test error with the wrong table name
+# Validation test error with the wrong schema name
 statement error
 CREATE EXTERNAL TABLE missing_schema
 	FROM postgres