Error 1046 occurs when a query is executed without a default database being selected in the current MySQL session.
MySQL Error 1046: ER_NO_DB_ERROR happens when you run a statement without choosing a database. Fix it by running USE your_database; or by fully qualifying tables (database.table).
No database selected
MySQL raises the ER_NO_DB_ERROR condition when a command requires a target schema but the session has no default database. The server cannot resolve unqualified table names, so it stops and returns SQLSTATE 3D000.
Developers typically meet this error after connecting with the mysql client or from an app that connects without issuing a USE statement.
It also appears inside scripts that rely on a removed or renamed database.
The error triggers on any statement that references tables or views without database prefixes: SELECT, INSERT, UPDATE, DELETE, CREATE TABLE LIKE, and many admin commands. If no database is selected, MySQL aborts execution immediately.
Leaving sessions without a default schema slows workflows, breaks automation pipelines, and risks executing queries on the wrong database when one is later chosen implicitly.
Prompt correction restores reliability and guards production data.
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Sessions opened through the mysql CLI, scripts, or language drivers often omit USE db_name;, leaving MySQL without context.
Automation that selects an old schema name fails once the schema no longer exists, surfacing the no-database error.
Accounts that cannot access the intended schema will see the error when USE db_name; is denied, leaving them without a default.
DSNs missing the database parameter connect successfully but lack a default schema for subsequent statements.
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No. Unless the connection string or startup option specifies a schema, MySQL leaves the session without a default database.
No. Every statement that references unqualified objects needs a schema. You can only avoid USE by fully qualifying names.
Yes, if the schema exists and the user has privileges. Otherwise, MySQL returns different errors like 1049 or 1044.
Galaxy automatically inserts USE db_name or qualifies table names based on your editor context, preventing ER_NO_DB_ERROR before execution.
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