Neat. For production, you might want to check the type on function arguments before using them.
Is it working fairly fast on inserts? That is, I presume, if this is intended for bypassing restrictions on the DEFAULT clause (expr) of column-constraint in a CREATE TABLE statement: https://www.sqlite.org/lang_createtable.html On Thu, Aug 3, 2017 at 3:35 PM, Sylvain Pointeau <sylvain.point...@gmail.com > wrote: > Hello, > > please find below my implementation of a sequence, I am open for any > critic! > > Best regards, > Sylvain > > ------------------------------------------------------------------- > > #include "sqlite3ext.h" > SQLITE_EXTENSION_INIT1 > > void sp_seq_init(sqlite3_context *context, int argc, sqlite3_value **argv) > { > int rc = 0; > sqlite3_stmt *stmt; > sqlite3 *db = sqlite3_context_db_handle(context); > > const unsigned char* seq_name = sqlite3_value_text(argv[0]); > long seq_init_val = sqlite3_value_int64(argv[1]); > long seq_inc_val = argc < 3 ? 1 : sqlite3_value_int64(argv[2]); > > rc = sqlite3_exec(db, "CREATE TABLE IF NOT EXISTS SP_SEQUENCE ( " \ > " SEQ_NAME TEXT NOT NULL PRIMARY KEY, " \ > " SEQ_VAL INTEGER NOT NULL, " \ > " SEQ_INC INTEGER NOT NULL " \ > " )", 0, 0, 0); > > if( rc != SQLITE_OK ) { > sqlite3_result_error(context, sqlite3_errmsg(db), -1); > return; > } > > > sqlite3_prepare_v2(db, "insert or replace into sp_sequence (seq_name, > seq_val, seq_inc) values (?, ?, ?)", -1, &stmt, 0); > > sqlite3_bind_text(stmt, 1, seq_name, -1, SQLITE_STATIC); > sqlite3_bind_int64(stmt, 2, seq_init_val); > sqlite3_bind_int64(stmt, 3, seq_inc_val); > > rc = sqlite3_step(stmt); > > sqlite3_finalize(stmt); > > if (rc != SQLITE_DONE) { > sqlite3_result_error(context, sqlite3_errmsg(db), -1); > return; > } > > sqlite3_result_int64( context, seq_init_val ); > } > > void sp_seq_nextval(sqlite3_context *context, int argc, sqlite3_value > **argv) { > int rc = 0; > sqlite3_stmt *stmt; > sqlite3 *db = sqlite3_context_db_handle(context); > long seq_val = 0; > > const unsigned char* seq_name = sqlite3_value_text(argv[0]); > > sqlite3_prepare_v2(db, "update sp_sequence set seq_val = seq_val + > seq_inc where seq_name = ?", -1, &stmt, 0); > > sqlite3_bind_text(stmt, 1, seq_name, -1, SQLITE_STATIC); > > rc = sqlite3_step(stmt); > > sqlite3_finalize(stmt); > > if (rc != SQLITE_DONE) { > sqlite3_result_error(context, sqlite3_errmsg(db), -1); > return; > } > > sqlite3_prepare_v2(db, "select seq_val from sp_sequence where seq_name = > ?", -1, &stmt, 0); > > sqlite3_bind_text(stmt, 1, seq_name, -1, SQLITE_STATIC); > > rc = sqlite3_step(stmt); > > if( rc == SQLITE_ROW) { > seq_val = sqlite3_column_int64(stmt, 0); > } > > sqlite3_finalize(stmt); > > if (rc != SQLITE_ROW) { > if( rc == SQLITE_DONE ) sqlite3_result_error(context, "sequence name > does not exist", -1); > else sqlite3_result_error(context, sqlite3_errmsg(db), -1); > return; > } > > sqlite3_result_int64( context, seq_val ); > } > > > int sqlite3_extension_init( > sqlite3 *db, > char **pzErrMsg, > const sqlite3_api_routines *pApi > ){ > SQLITE_EXTENSION_INIT2(pApi) > sqlite3_create_function(db, "seq_init_inc", 3, SQLITE_UTF8, 0, > sp_seq_init, 0, 0); > sqlite3_create_function(db, "seq_init", 2, SQLITE_UTF8, 0, sp_seq_init, 0, > 0); > sqlite3_create_function(db, "seq_nextval", 1, SQLITE_UTF8, 0, > sp_seq_nextval, 0, 0); > return 0; > } > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
