$SQLTimeout

gives the default time in seconds that DatabaseLink waits while opening connections and executing database queries.

范例

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Wolfram Language code: Needs["DatabaseLink`"]

Wolfram Language code: $SQLTimeout

Set a timeout value for a query:

Wolfram Language code: conn = OpenSQLConnection[JDBC["MySQL(Drizzle)", "localhost/sandbox"]]

Wolfram Language code: Block[{$SQLTimeout = 1}, AbsoluteTiming@SQLExecute[conn, "SELECT SLEEP(3);"]]

Wolfram Language code: CloseSQLConnection[conn];

Wolfram Language code: Needs["DatabaseLink`"]

Setting $SQLTimeout affects the default timeout for all DatabaseLink functions with a "Timeout" option:

Wolfram Language code: $SQLTimeout = 30;

Wolfram Language code: "Timeout" /. Options /@ {OpenSQLConnection, SQLDropTable, SQLUpdate}

Wolfram Language code: Needs["DatabaseLink`"]

Not all JDBC drivers implement timeout-related methods. Setting $SQLTimeout (or the "Timeout" option) will have no effect with certain drivers:

Wolfram Language code:

Block[{$SQLTimeout = 1}, AbsoluteTiming@OpenSQLConnection[JDBC["PostgreSQL", "1.2.3.4/nonexistent"]]
	]

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