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Enhanced User Experience with Embedded SQL and CLI

Explore how Embedded SQL within host languages improves usability, connectivity, and data exchange in DBMS operations. Learn about the Call-level Interface (CLI) standardization and the benefits it offers in SQL programming.

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Enhanced User Experience with Embedded SQL and CLI

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  1. Embedded SQL and the CLI Chapter 7.7

  2. SQL is very high-level, but... • Too low level for end-users • Requires detailed knowledge of DB schema • Unsatisfactory as a user interface • Solution: End user sees only an interface written by a DB programmer • "host language" such as COBOL, C, VB, etc. • program contains the SQL, hard-coded or dynamically generated

  3. "Impedance" Mismatch • Host language doesn't understand SQL • Host language data types vs SQL data types • Conventional imperative languages don't match declarative outlook of SQL • Whole table operations • Say "what" not "how" • Must somehow connect to the DBMS

  4. Solutions • "Cursor" concept • expose one row at a time • process a result table like a sequential file • Embedded SQL • Standard SQL statements in host source, translated by preprocessor • DBMS via an API (Application Programming interface) • Calls use host language conventions

  5. CLI: Call-level Interface • DB APIs have been around for decades • relational and non-relational • "The" CLI is a recently standardized API • Calls to SQL in host language syntax • Added to the SQL Standard in 1995 • Based on Microsoft ODBC (Open Database Connectivity) • Program declares a struct (class) for each row type (i.e. for each table) • "data exchange" supports data type conversion between DB format and host (e.g. C++)

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