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  1. Integrations
  2. Database tools and SQL
  3. Troubleshooting
  4. Cannot connect to a database

Cannot connect to a database

Last modified: 20 April 2022

Step 1. Check your network settings

Databases can work locally, on a server, or in the cloud. For server and cloud databases, you need a network connection. To verify that connection is available, use ping and telnet commands.

With the ping command, you can ensure that the destination computer is reachable from the source computer. Open a command line and type the following command: ping -a <host_IP>, where -a is a command option that resolves addresses to hostnames (if it is possible). If you use hostnames with the ping command, a hostname is resolved to the IP address. For example, ping -a example.com resolves to PING example.com (93.184.216.34).

ping -a <host_IP>
Test connection with the ping command

With the telnet command, you can test connectivity to remote computers and issue commands. If you specify a port as a parameter for the telnet command, you can test connectivity to a remote host on the given port. If the connection is successful, you see the message: Connected to <host_IP>.

telnet <host_IP> <port_number>
Test connection with the telnet command

note

For security reasons, DBMS usually drops all telnet connections. The telnet command allows you to check if the port is opened for communication.

Step 2. Check your connection properties

Each database (MySQL, PostgreSQL, Oracle, or any other vendor) has its own connection settings. Most database include the connection settings:

  • Host: A hostname of a computer or other device that stores a database. It can be an IP address 127.0.0.1 or a domain name localhost.

  • Database: A name of the database to which you want to connect. You can find the database name in the settings of your database server, or you can ask your database administrator. In some cases, it is possible to run a query in a database command line to see names of all available databases. For example, in MySQL you can run SHOW DATABASES;.

    The SHOW DATABASES query

  • User: A name of a user that has sufficient privileges to perform actions with a database. Run a query in a database command line to see names of all available databases. For example, in MySQL you can run SHOW GRANTS;.

    The SHOW GRANTS query

  • Password: A password of the user.

  • Port: A number that identifies a connection point between hosts. Hosts use port numbers to determine to which application, service, or process a connection must be established. Different database vendors use different ports for their databases. The following list is a list of default port numbers.

    Vendor

    Default port

    Amazon Redshift

    5439

    Apache Derby

    1527

    Apache Cassandra

    9042

    Apache Hive

    10000 (Hive Server2) or 9083 (Hive Metastore)

    Azure SQL Database

    1433

    ClickHouse

    8123

    Couchbase Query Query Service

    11210

    Exasol

    8563

    Greenplum

    5432

    H2

    8082

    HSQLDB

    9001

    IBM Db2 LUW

    50000

    MariaDB

    3306

    Microsoft SQL Server

    1433 (TCP), 1434 (UDP might be required)

    MySQL

    3306

    Oracle

    1521

    PostgreSQL

    5432

    Snowflake

    443

    SQLite

    None

    Sybase ASE

    5000

    Vertica

    5433

    note

    Real port numbers might be different on your system. Verify that you use a correct port number with your database administrator.

Verify that the connection settings for the selected database connection are correct. For more information about creating or changing a database connection, see Database connection.

Step 3. Check the driver version

With a JDBC driver, you can interact with a database management system (DBMS) from AppCode. Each DBMS requires its own JDBC driver. Ensure that the driver version and the DBMS version are compatible with each other.

From AppCode, you can download drivers for all supported vendors. You can check the full list of supported vendors in the Drivers list . Alternatively, you can add your own driver to an existing vendor, or create a new driver entry for the vendor that is not on the Drivers list.

To open the Drivers list, in the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon or press ⇧ ⏎.

Download a driver and select the driver version

To download drivers from the JetBrains FTP server, select a vendor from the Drivers list, and click the Download ver. <version_number> link in the Driver files pane.

To change the driver version, click the ver. <version_number> link in the Driver files pane and select the driver version that you need.

The Drivers list and driver settings

    Using user driver files

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. In the Data Sources and Drivers dialog, ensure that you are on the Drivers tab.

    3. In the Data Sources and Drivers dialog, click the Add icon (The Add icon).

    4. In the Name field, type the name of the driver.

    5. In the Driver Files pane, click the Add icon (The Add icon) and select Custom JARs….

    6. Navigate to the JAR file of the JDBC driver, select it, and click OK.

    7. In the Class field, specify the value that you want to use for the driver.

    8. Click Apply.

    9. To create a data source from the driver's dialog, click Create Data Source.

      https://resources.jetbrains.com/help/img/idea/2022.2/db_create_user_driver_connection.png
      Gif

    Configure a JDBC driver from the existing connection

    You can add libraries to the existing driver or replace the driver completely.

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. In the Data Sources and Drivers dialog, click the Drivers tab, and select a data source where you want to change a driver.

    3. Click the Driver link in data source settings.

    4. Click the provided driver entry, and click Remove (the Remove button).

      To revert changes, click the Roll back Changes icon (the Roll back Changes icon) that is in the lower-right part of the window.

    5. In the Driver files pane, click the Add icon (The Add icon) and select Custom JARs….

    6. In the file browser, navigate to the JAR file of the JDBC driver, select it, and click OK.

    7. In the Class field, specify the value that you want to use for the driver .

    8. Click Apply.

      Add a user driver to an existing connection

    Step 4. Check if the connection with SSH or SSL is required

    To make a connection to a database more secure, some services require SSH or SSL usage.

    SSL

    The following procedure describes the SSL configuration that suits most databases. For some databases, you need to use another approach for a successful connection. You can see configuration examples for Cassandra and Heroku Postgres in the DataGrip documentation.

    Connect to a database with SSL

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. On the Data Sources tab, select a data source that you want to modify.

    3. Click the SSH/SSL tab and select the Use SSL checkbox.

    4. In the CA file field, navigate to the CA certificate file (for example, mssql.pem).

    5. In the Client certificate file field, navigate to the client certificate file (for example, client-cert.pem).

    6. In the Client key file field, navigate to the client key file (for example, client-key.pem).

    7. From the Mode list, select the verification mode:

      • Require: verifies that the server accepts SSL connections for this IP address and recognizes the client certificate.

      • Verify CA: verifies the server by checking the certificate chain up to the root certificate that is stored on the client.

      • Full Verification: verifies the server host to ensure that it matches the name stored in the server certificate. The SSL connection fails if the server certificate cannot be verified.

    8. To ensure that the connection to the data source is successful, click Test Connection.

      Connect to a database with SSL

    note

    It is recommended to use PEM certificates.

    note

    With self-signed certificates and in some cases with certificates issued by the trusted root entity, you might experience errors when you use the latest JDBC driver version. The SSL connection might fail if your Java keystore does not accept the certificate chains. As a temporary solution, try to downgrade the JDBC driver (for example, for the MySQL connector, you need to switch to the 5.1.40 version.)

    Disable SSL connection to a database

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. On the Data Sources tab, select a data source that you want to modify.

    3. Click the SSH/SSL tab and clear the Use SSL checkbox.

    4. Click Apply.

    Copy SSL settings from other data sources

    If you configured SSL settings for one data source, you can copy them for another data source.

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. On the Data Sources tab, select a data source that you want to modify.

    3. Click the SSH/SSL tab and select the Use SSL checkbox.

    4. Click the Copy from … link and select the configuration that you want to copy.

    SSH

    note

    After you have configured the SSH settings, on the General tab, use the host address and the database port, not localhost.

    Secure Shell or SSH is a network protocol that is used to encrypt a connection between a client and a server.

    All created SSH connections are shared between all the data sources that you have in a project. If you do not want to share a connection between projects, select the Visible only for this project checkbox in the SSH connection settings.

    Connect to a database with SSH

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. Select a data source profile where you want to change connection settings.

    3. Click the SSH/SSL tab and select the Use SSH tunnel checkbox.

    4. Click the Add SSH configuration button (the Add SSH configuration).

    5. In the SSH dialog, click the Add button.

    6. If you do not want to share the configuration between projects, select the Visible only for this project checkbox.

    7. In Host, Username, and Port fields, specify your connection details.

    8. From the Authentication type list, you can select an authentication method:

      • Password: to access the host with a password. To save the password in AppCode, select the Save password checkbox.

      • Key pair (OpenSSH or PuTTY): to use SSH authentication with a key pair. To apply this authentication method, you must have a private key on the client machine and a public key on the remote server. AppCode supports private keys that are generated with the OpenSSH utility.

        Specify the path to the file where your private key is stored and type the passphrase (if any) in the corresponding fields. To have AppCode remember the passphrase, select the Save passphrase checkbox.

      • If your SSH keys are managed by a credentials helper application (for example, ssh-agent), choose OpenSSH config and authentication agent.

      SSH and SSL settings of a data source

    tip

    See the Generating a new SSH key and adding it to the ssh-agent tutorial for details on working with SSH keys.

    Disable SSH connection to a database

    1. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon The Data Source Properties icon.

    2. Select a data source profile where you want to change connection settings.

    3. Click the SSH/SSL tab and clear the Use SSH tunnel checkbox.

    4. Click Apply.

    Create the SSH tunnel with the ssh-agent

    Run all commands for ssh-agent in the command line.

    1. Ensure that ssh-agent is running. 

      ssh-agent

    2. Add your key to the agent (in the following example, the key path is ~/.ssh/id_rsa). 

      ssh-add ~/.ssh/id_rsa

    3. (Optional) On macOS, you can add -K option to the ssh-add command to store passphrases in your keychain. On macOS Sierra and later, you need to create the config file in ~/.ssh/ with the following text:

      Host *
UseKeychain yes
AddKeysToAgent yes
IdentityFile ~/.ssh/id_rsa

      If you have other private keys in the .ssh directory, add an IdentityFile line for each key. For example, if the second key has the id_ed25519 name, add IdentityFile ~/.ssh/id_ed25519 as an additional line for the second private key.

    4. List all added keys. 

      ssh-add -L

    5. In the Database tool window (View | Tool Windows | Database), click the Data Source Properties icon the Data Source Properties icon on the toolbar.

    6. Select a data source profile where you want to change connection settings.

    7. Click the SSH/SSL tab and select the Use SSH tunnel checkbox.

    8. From the Auth type list, select OpenSSH config and authentication agent.

    9. In Proxy host, Proxy user, and Port fields, specify connection details.

    10. To ensure that the connection to the data source is successful, click Test Connection.

    Create the SSH tunnel with the ssh-agent (macOS and Linux)

    Step 5. Write to us if you still need help

    Write to the AppCode team

    • Email our team at appcode-support@jetbrains.com. Describe your problem, and attach all available materials that can speed up troubleshooting (code samples, screenshots, logs, animations, videos, and other materials).