Connection string formats for MySQL, PostgreSQL and Redis, and where they break

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Database drivers all accept URLs, but MySQL, PostgreSQL and Redis interpret those URLs differently, so a string copied between them often fails with unclear errors. The article lays out the shared structure of the format and then the specifics: how each database uses the path segment, expresses TLS, and sets default ports. It highlights traps such as MySQL's REQUIRED mode encrypting without verifying certificates, Postgres's prefer setting silently downgrading, and Redis treating a missing colon as a password-only field. Special characters in passwords must be percent-encoded, while IPv6 hosts need brackets and Unix sockets have no standard URL form. The piece is a practical reference for developers moving between database stacks.

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