Index: ext/misc/json1.c
==================================================================
--- ext/misc/json1.c
+++ ext/misc/json1.c
@@ -1208,10 +1208,29 @@
 #endif /* SQLITE_DEBUG */
 
 /****************************************************************************
 ** Scalar SQL function implementations
 ****************************************************************************/
+
+/*
+** Implementation of the json_QUOTE(VALUE) function.  Return a JSON value
+** corresponding to the SQL value input.  Mostly this means putting 
+** double-quotes around strings and returning the unquoted string "null"
+** when given a NULL input.
+*/
+static void jsonQuoteFunc(
+  sqlite3_context *ctx,
+  int argc,
+  sqlite3_value **argv
+){
+  JsonString jx;
+
+  jsonInit(&jx, ctx);
+  jsonAppendValue(&jx, argv[0]);
+  jsonResult(&jx);
+  sqlite3_result_subtype(ctx, JSON_SUBTYPE);
+}
 
 /*
 ** Implementation of the json_array(VALUE,...) function.  Return a JSON
 ** array that contains all values given in arguments.  Or if any argument
 ** is a BLOB, throw an error.
@@ -2122,10 +2141,11 @@
     { "json_array_length",    1, 0,   jsonArrayLengthFunc   },
     { "json_array_length",    2, 0,   jsonArrayLengthFunc   },
     { "json_extract",        -1, 0,   jsonExtractFunc       },
     { "json_insert",         -1, 0,   jsonSetFunc           },
     { "json_object",         -1, 0,   jsonObjectFunc        },
+    { "json_quote",           1, 0,   jsonQuoteFunc         },
     { "json_remove",         -1, 0,   jsonRemoveFunc        },
     { "json_replace",        -1, 0,   jsonReplaceFunc       },
     { "json_set",            -1, 1,   jsonSetFunc           },
     { "json_type",            1, 0,   jsonTypeFunc          },
     { "json_type",            2, 0,   jsonTypeFunc          },

Index: test/json101.test
==================================================================
--- test/json101.test
+++ test/json101.test
@@ -353,8 +353,37 @@
   SELECT b FROM t8;
 } {{["abc\u0001\u0002\u0003\u0004\u0005\u0006\u0007\b\t\n\u000b\f\r\u000e\u000f\u0010\u0011\u0012\u0013\u0014\u0015\u0016\u0017\u0018\u0019\u001a\u001b\u001c\u001d\u001e\u001f !\"#xyz"]}}
 do_execsql_test json-8.2 {
   SELECT a=json_extract(b,'$[0]') FROM t8;
 } {1}
+
+# The json_quote() function transforms an SQL value into a JSON value.
+# String values are quoted and interior quotes are escaped.  NULL values
+# are rendered as the unquoted string "null".
+#
+do_execsql_test json-9.1 {
+  SELECT json_quote('abc"xyz');
+} {{"abc\"xyz"}}
+do_execsql_test json-9.2 {
+  SELECT json_quote(3.14159);
+} {3.14159}
+do_execsql_test json-9.3 {
+  SELECT json_quote(12345);
+} {12345}
+do_execsql_test json-9.4 {
+  SELECT json_quote(null);
+} {"null"}
+do_catchsql_test json-9.5 {
+  SELECT json_quote(x'30313233');
+} {1 {JSON cannot hold BLOB values}}
+do_catchsql_test json-9.6 {
+  SELECT json_quote(123,456)
+} {1 {wrong number of arguments to function json_quote()}}
+do_catchsql_test json-9.7 {
+  SELECT json_quote()
+} {1 {wrong number of arguments to function json_quote()}}
+
+
+
 
 
 finish_test