---
# OpenLink MCP Server for JDBC
A lightweight Java-based MCP (Model Context Protocol) server for JDBC built with **Quakrus**.
This server is compatible with Virtuoso DBMS and any other DBMS backend that has a JDBC driver.
---
## Features
- **Get Schemas**: Fetch and list all schema names from the connected database.
- **Get Tables**: Retrieve table information for specific schemas or all schemas.
- **Describe Table**: Generate a detailed description of table structures, including:
- Column names and data types
- Nullable attributes
- Primary and foreign keys
- **Search Tables**: Filter and retrieve tables based on name substrings.
- **Execute Stored Procedures**: _A Virtuoso-specific feature!_ Execute stored procedures and retrieve results.
- **Execute Queries**:
- JSONL result format: Optimized for structured responses.
- Markdown table format: Ideal for reporting and visualization.
---
## Prerequisites
MCP server requires Java 21 or above.
---
## Installation
Clone this repository:
```bash
git clone https://github.com/OpenLinkSoftware/mcp-jdbc-server.git
cd mcp-jdbc-server
```
## Environment Variables
Update your `.env` by overriding these defaults to match your preferences:
```
jdbc.url=jdbc:virtuoso://localhost:1111
jdbc.user=dba
jdbc.password=dba
jdbc.api_key=xxx
```
---
## Configuration
For **Claude Desktop** users using Virtuoso and its JDBC driver:
Add the following to `claude_desktop_config.json`:
```json
{
"mcpServers": {
"my_database": {
"command": "java",
"args": ["-jar", "/path/to/mcp-jdbc-server/MCPServer-1.0.0-runner.jar"],
"env": {
"jdbc.url": "jdbc:virtuoso://localhost:1111",
"jdbc.user": "username",
"jdbc.password": "password",
"jdbc.api_key": "sk-xxx"
}
}
}
}
```
For **Claude Desktop** users using another JDBC driver or a combination of drivers:
Add the following, edited to suit your local environment, to `claude_desktop_config.json`:
```json
"jdbc": {
"command": "java",
"args": [
"-cp",
"/path/to/mcp-jdbc-server/MCPServer-1.0.0-runner.jar:/path/to/jdbc_driver1.jar:/path/to/jdbc_driverN.jar",
"io.quarkus.runner.GeneratedMain"
],
"env": {
"jdbc.url": "jdbc:virtuoso://localhost:1111",
"jdbc.user": "dba",
"jdbc.password": "dba"
}
}
```
---
## Use
### Tools Provided
After successful installation, the following tools will be available to MCP client applications.
#### Overview
| name | description |
|:--- |:---|
|`jdbc_get_schemas` | List database schemas accessible to connected database management system (DBMS). |
|`jdbc_get_tables` | List tables associated with a selected database schema. |
|`jdbc_describe_table` | Provide the description of a table associated with a designated database schema. This includes information about column names, data types, nulls handling, autoincrement, primary key, and foreign keys. |
|`jdbc_filter_table_names` | List tables, based on a substring pattern from the `q` input field, associated with a selected database schema. |
|`jdbc_query_database` | Execute a SQL query and return results in JSONL format. |
|`jdbc_execute_query` | Execute a SQL query and return results in JSONL format. |
|`jdbc_execute_query_md` | Execute a SQL query and return results in Markdown table format. |
|`jdbc_spasql_query` | _A Virtuoso-specific feature!_ Execute a SPASQL query and return results. |
|`jdbc_sparql_query` | _A Virtuoso-specific feature!_ Execute a SPARQL query and return results. |
|`jdbc_virtuoso_support_ai`| _A Virtuoso-specific feature!_ Interact with LLMs through the Virtuoso Support Assistant/Agent. |
#### Detailed Description
- **`jdbc_get_schemas`**
- Retrieve and return a list of all schema names from the connected database.
- Input parameters:
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns a JSON string array of schema names.
- **`jdbc_get_tables`**
- Retrieve and return a list containing information about tables in a specified schema. If no schema is provided, uses the connection's default schema.
- Input parameters:
- `schema` (string, optional): Database schema to filter tables. Defaults to connection default.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns a JSON string containing table information (e.g., `TABLE_CAT`, `TABLE_SCHEM`, `TABLE_NAME`, `TABLE_TYPE`).
- **`jdbc_filter_table_names`**
- Filters and returns information about tables whose names contain a specific substring.
- Input parameters:
- `q` (string, required): The substring to search for within table names.
- `schema` (string, optional): Database schema to filter tables. Defaults to connection default.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns a JSON string containing information for matching tables.
- **`jdbc_describe_table`**
- Retrieve and return detailed information about the columns of a specific table.
- Input parameters:
- `schema` (string, required): The database schema name containing the table.
- `table` (string, required): The name of the table to describe.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns a JSON string describing the table's columns (e.g., `COLUMN_NAME`, `TYPE_NAME`, `COLUMN_SIZE`, `IS_NULLABLE`).
- **`jdbc_query_database`**
- Execute a standard SQL query and return the results in JSON format.
- Input parameters:
- `query` (string, required): The SQL query string to execute.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns query results as a JSON string.
- **`jdbc_query_database_md`**
- Execute a standard SQL query and return the results formatted as a Markdown table.
- Input parameters:
- `query` (string, required): The SQL query string to execute.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns query results as a Markdown table string.
- **`jdbc_query_database_jsonl`**
- Execute a standard SQL query and return the results in JSON Lines (JSONL) format (one JSON object per line).
- Input parameters:
- `query` (string, required): The SQL query string to execute.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns query results as a JSONL string.
- **`jdbc_spasql_query`**
- _A Virtuoso-specific feature!_
- Execute a SPASQL (SQL/SPARQL hybrid) query return results.
- Input parameters:
- `query` (string, required): The SPASQL query string.
- `max_rows` (number, optional): Maximum number of rows to return. Defaults to `20`.
- `timeout` (number, optional): Query timeout in milliseconds. Defaults to `30000` (i.e., 30 seconds).
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns the result from the underlying stored procedure call (e.g., `Demo.demo.execute_spasql_query`).
- **`jdbc_sparql_query`**
- _A Virtuoso-specific feature!_
- Execute a SPARQL query and return results.
- Input parameters:
- `query` (string, required): The SPARQL query string.
- `format` (string, optional): Desired result format. Defaults to `'json'`.
- `timeout` (number, optional): Query timeout in milliseconds. Defaults to `30000` (i.e., 30 seconds).
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns the result from the underlying function call (e.g., `"UB".dba."sparqlQuery"`).
- **`jdbc_virtuoso_support_ai`**
- _A Virtuoso-specific feature!_
- Utilizes a Virtuoso-specific AI Assistant function, passing a prompt and optional API key.
- Input parameters:
- `prompt` (string, required): The prompt text for the AI function.
- `api_key` (string, optional): API key for the AI service. Defaults to `"none"`.
- `user` (string, optional): Database username. Defaults to `"demo"`.
- `password` (string, optional): Database password. Defaults to `"demo"`.
- `url` (string, optional): JDBC URL connection string.
- Returns the result from the AI Support Assistant function call (e.g., `DEMO.DBA.OAI_VIRTUOSO_SUPPORT_AI`).
---
### Basic Use & Troubleshooting
#### MCP Inspector Connecting to Virtuoso's ODBC Driver
For basic MCP client use and troubleshooting, use the MCP Inspector as follows:
1. Install the MCP Inspector:
```bash
npm install -g @modelcontextprotocol/inspector
```
2. Start the inspector:
```bash
npx @modelcontextprotocol/inspector java -jar /path/to/mcp-jdbc-server/MCPServer-1.0.0-runner.jar
```
Access the URL returned by the inspector to troubleshoot MCP server interactions.
#### MCP Inspector Connecting to additional Drivers
For basic MCP client use and troubleshooting, use the MCP Inspector as follows:
1. Install the JDBC Driver(s), ensuring their JAR files are registered with the host operating system's Java Virtual Machine (JVM) via `$CLASSPATH`. For instance:
```bash
export CLASSPATH=$CLASSPATH:/path/to/driver1.jar:/path/to/driver2.jar:/path/to/driverN.jar
```
2. Start the inspector using the following command-line arguments:
```bash
npx @modelcontextprotocol/inspector java -cp MCPServer-1.0.0-runner.jar:/path/to/driver1.jar:/path/to/driver2.jar:/path/to/driverN.jar io.quarkus.runner.GeneratedMain
```
#### Use Example based on Oracle and Informix Drivers
0. Assuming the following JDBC Driver information:
- **Oracle JDBC Driver URL Template**
```bash
jdbc:oracle:thin:@<hostname>:[port]:<SERVICEID>
```
- **Informix JDBC Driver URL Template**
```bash
jdbc:informix-sqli://<hostname>:<port>/<database></database>:<INFORMIXSERVER>=<SERVICEID>
```
1. Install the Oracle (`ojdbc17.jar`) and/or Informix (`jdbc-15.0.0.1.1.jar`) JDBC Drivers, and ensure their JAR files are registered with the host operating system's Java Virtual Machine (JVM) via `$CLASSPATH`. For instance:
```bash
export CLASSPATH=$CLASSPATH:/path/to/Java/Extensions/jdbc-15.0.0.1.1.jar
export CLASSPATH=$CLASSPATH:/path/to/Java/Extensions/ojdbc17.jar
```
2. Start the inspector using the following command-line arguments:
```bash
npx @modelcontextprotocol/inspector java -cp MCPServer-1.0.0-runner.jar:/path/to/Java/Extensions/ojdbc17.jar:/path/to/Java/Extensions/jdbc-15.0.0.1.1.jar io.quarkus.runner.GeneratedMain
```
3. Access the URL returned by the inspector and then use the `jdbc_execute_query` operation to query the target database, by providing actual values for the following input field templates:
- JDBC URL
- User
- Password
- Query
