Microsoft SQL Server

Interact with Microsoft SQL Server databases using the mssql CLI. All commands output JSON by default for reliable parsing.

IMPORTANT — Agent safety rules:

1. Never run mssql sql-dangerous without explicit user approval. Always present the full SQL query to the user and explain what it does before executing. This command can modify or destroy data (INSERT, UPDATE, DELETE, DROP, etc.).
2. Prefer mssql sql for reads. Use the read-only mssql sql command for SELECT queries. It blocks dangerous statements automatically.
3. Prefer mssql schema over raw queries when you need table structure information.
4. If you are unsure of the schema, use mssql schema to check first — do not guess column or table names.

Setup

Add a server connection

mssql server add --name mydb --server localhost --database MyDatabase --user sa --password "secret" --format json
mssql server add --name mydb --server db.example.com --database MyDatabase --windows-auth --trust-cert --format json

The first server added is automatically set as the default. Config is saved to ~/.config/mssql-cli/config.json.

Environment variables

Environment variables create a transient connection that takes priority over the config file:

export MSSQL_SERVER=localhost
export MSSQL_DATABASE=MyDatabase
export MSSQL_USER=sa
export MSSQL_PASSWORD=secret
export MSSQL_PORT=1433          # optional, default 1433
export MSSQL_ENCRYPT=true       # optional
export MSSQL_TRUST_CERT=true    # optional
export MSSQL_WINDOWS_AUTH=true  # optional, use instead of user/password

Server Management

List configured servers

mssql server list --format json --pretty

Set the default server

mssql server default --name mydb --format json

Test connectivity

mssql server test --format json
mssql server test --name mydb --format json

Remove a server

mssql server remove --name mydb --format json

View or update global settings

mssql server config --format json
mssql server config --max-rows 500 --format json

The maxRows setting (default: 100) limits the number of rows returned by queries. A truncation warning is included when results are capped.

Queries (Read-Only)

Use mssql sql for SELECT queries. This command blocks any statements that could modify data (INSERT, UPDATE, DELETE, DROP, CREATE, ALTER, TRUNCATE, MERGE, EXEC, etc.) and directs you to use sql-dangerous instead.

mssql sql --query "SELECT TOP 10 * FROM Users" --format json --pretty
mssql sql --query "SELECT COUNT(*) AS total FROM Orders WHERE Status = 'Pending'" --format json
mssql sql --query "SELECT u.Name, COUNT(o.Id) AS OrderCount FROM Users u JOIN Orders o ON u.Id = o.UserId GROUP BY u.Name" --server mydb --format json --pretty
mssql sql --file report.sql --format json --pretty

Use --query for inline SQL or --file to read SQL from a .sql file. These options are mutually exclusive.

Results are limited to the configured maxRows (default 100). If more rows exist, the output includes a truncation warning.

Queries (Dangerous — Modifying)

Agents: NEVER run this command without first showing the query to the user and receiving explicit approval.

Use mssql sql-dangerous for statements that modify data or schema. This command has no safety restrictions.

mssql sql-dangerous --query "INSERT INTO Users (Name, Email) VALUES ('Alice', 'alice@example.com')" --format json
mssql sql-dangerous --query "UPDATE Orders SET Status = 'Shipped' WHERE Id = 42" --format json
mssql sql-dangerous --query "DELETE FROM Sessions WHERE ExpiresAt < GETDATE()" --format json
mssql sql-dangerous --query "CREATE INDEX IX_Users_Email ON Users(Email)" --format json
mssql sql-dangerous --file migration.sql --format json

As with mssql sql, use --query for inline SQL or --file to read from a file (mutually exclusive).

The output includes rowsAffected count in addition to any result rows.

Schema Inspection

Get full schema details for one or more tables — columns, data types, primary keys, foreign keys (both directions), and indexes.

mssql schema Users --format json --pretty
mssql schema Users Orders --format json --pretty
mssql schema dbo.Users sales.Orders --format json --pretty

Tables default to the dbo schema if not specified. Use schema.table notation for other schemas.

Output Format

All commands support --format json (compact, default) or --format text (human-readable tables). Add --pretty for indented JSON.

Exit codes: 0 = success, 1 = error. Errors are written to stderr as JSON.

Common Workflows

Explore a table before querying:

mssql schema Users --format json --pretty
mssql sql --query "SELECT TOP 5 * FROM Users" --format json --pretty

Check row counts across tables:

mssql sql --query "SELECT 'Users' AS TableName, COUNT(*) AS Rows FROM Users UNION ALL SELECT 'Orders', COUNT(*) FROM Orders" --format json --pretty

Safe data fix (always confirm with user first):

# 1. Check current state
mssql sql --query "SELECT Id, Email FROM Users WHERE Id = 42" --format json --pretty
# 2. After user approval, apply the fix
mssql sql-dangerous --query "UPDATE Users SET Email = 'new@example.com' WHERE Id = 42" --format json
# 3. Verify the change
mssql sql --query "SELECT Id, Email FROM Users WHERE Id = 42" --format json --pretty