add support for LIMIT clause in SQL engine

include/mdbsql.h

@@ -43,6 +43,8 @@ typedef struct {
 	unsigned char *kludge_ttable_pg;
 	long max_rows;
 	char error_msg[1024];
+	int limit;
+	long row_count;
 } MdbSQL;
 
 typedef struct {
@@ -99,6 +101,7 @@ extern void mdb_sql_bind_all(MdbSQL *sql);
 extern int mdb_sql_fetch_row(MdbSQL *sql, MdbTableDef *table);
 extern int mdb_sql_add_temp_col(MdbSQL *sql, MdbTableDef *ttable, int col_num, char *name, int col_type, int col_size, int is_fixed);
 extern void mdb_sql_bind_column(MdbSQL *sql, int colnum, void *varaddr, int *len_ptr);
+extern int mdb_sql_add_limit(MdbSQL *sql, char *limit);
 
 #ifdef __cplusplus
   }

src/sql/lexer.l

@@ -45,12 +45,14 @@ null		{ return NUL; }
 (<=)		{ return LTEQ; }
 (>=)		{ return GTEQ; }
 like		{ return LIKE; }
+limit	{ return LIMIT; }
 [ \t\r]	;
 
 \"[^"]*\"\"  {
 		yyless(yyleng-1);
 		yymore();
 	}
+
 \"[^"]*\"  {
 		int ip, op, ilen;
 		ilen = strlen(yytext);

src/sql/mdbsql.c

@@ -429,6 +429,17 @@ int mdb_sql_add_column(MdbSQL *sql, char *column_name)
 	sql->num_columns++;
 	return 0;
 }
+int mdb_sql_add_limit(MdbSQL *sql, char *limit)
+{
+	sql->limit = atoi(limit);
+	return 0;
+}
+
+int mdb_sql_add_function1(MdbSQL *sql, char *func_name, char *arg1)
+{
+	fprintf(stderr, "calling function %s with %s", func_name, arg1);
+	return 0;
+}
 int mdb_sql_add_table(MdbSQL *sql, char *table_name)
 {
 	MdbSQLTable *t;
@@ -509,6 +520,8 @@ void mdb_sql_reset(MdbSQL *sql)
 
 	sql->all_columns = 0;
 	sql->max_rows = -1;
+	sql->row_count = 0;
+	sql->limit = 0;
 }
 static void print_break(int sz, int first)
 {
@@ -762,7 +775,14 @@ mdb_sql_bind_all(MdbSQL *sql)
 int
 mdb_sql_fetch_row(MdbSQL *sql, MdbTableDef *table)
 {
-	return mdb_fetch_row(table);
+	int rc = mdb_fetch_row(table);
+	if (rc) {
+		if (sql->row_count + 1 > sql->limit) {
+			return 0;
+		}
+		sql->row_count++;
+	}
+	return rc;
 }
 
 void 

src/sql/parser.y

@@ -42,7 +42,7 @@ static MdbSQL *g_sql;
 
 
 %token <name> IDENT NAME PATH STRING NUMBER 
-%token SELECT FROM WHERE CONNECT DISCONNECT TO LIST TABLES AND OR NOT
+%token SELECT FROM WHERE CONNECT DISCONNECT TO LIST TABLES AND OR NOT LIMIT
 %token DESCRIBE TABLE
 %token LTEQ GTEQ LIKE IS NUL
 
@@ -60,7 +60,7 @@ stmt:
 	;
 
 query:
-	SELECT column_list FROM table where_clause {
+	SELECT column_list FROM table where_clause limit_clause {
 			mdb_sql_select(_mdb_sql(NULL));	
 		}
 	|	CONNECT TO database { 
@@ -82,6 +82,11 @@ where_clause:
 	| WHERE sarg_list
 	;
 
+limit_clause:
+	/* empty */
+	| LIMIT NUMBER { mdb_sql_add_limit(_mdb_sql(NULL), $2); free($2); }
+	;
+
 sarg_list:
 	sarg 
 	| '(' sarg_list ')'

src/util/mdb-sql.c

@@ -253,7 +253,6 @@ dump_results(FILE *out, MdbSQL *sql, char *delimiter)
 {
 	unsigned int j;
 	MdbSQLColumn *sqlcol;
-	unsigned long row_count = 0;
 
 	if (headers) {
 		for (j=0;j<sql->num_columns-1;j++) {
@@ -266,8 +265,7 @@ dump_results(FILE *out, MdbSQL *sql, char *delimiter)
 		fprintf(out,"\n");
 		fflush(out);
 	}
-	while(mdb_fetch_row(sql->cur_table)) {
+	while(mdb_sql_fetch_row(sql, sql->cur_table)) {
-		row_count++;
   		for (j=0;j<sql->num_columns-1;j++) {
 			sqlcol = g_ptr_array_index(sql->columns,j);
 			fprintf(out, "%s%s", (char*)(sql->bound_values[j]),
@@ -279,7 +277,7 @@ dump_results(FILE *out, MdbSQL *sql, char *delimiter)
 		fflush(out);
 	}
 	if (footers) {
-		print_rows_retrieved(out, row_count);
+		print_rows_retrieved(out, sql->row_count);
 	}
 }
 
@@ -288,7 +286,6 @@ dump_results_pp(FILE *out, MdbSQL *sql)
 {
 	unsigned int j;
 	MdbSQLColumn *sqlcol;
-	unsigned long row_count = 0;
 
 	/* print header */
 	if (headers) {
@@ -316,8 +313,7 @@ dump_results_pp(FILE *out, MdbSQL *sql)
 	fflush(out);
 
 	/* print each row */
-	while(mdb_fetch_row(sql->cur_table)) {
+	while(mdb_sql_fetch_row(sql, sql->cur_table)) {
-		row_count++;
   		for (j=0;j<sql->num_columns;j++) {
 			sqlcol = g_ptr_array_index(sql->columns,j);
 			print_value(out, sql->bound_values[j],sqlcol->disp_size,!j);
@@ -334,7 +330,7 @@ dump_results_pp(FILE *out, MdbSQL *sql)
 	fprintf(out,"\n");
 	fflush(out);
 	if (footers) {
-		print_rows_retrieved(out, row_count);
+		print_rows_retrieved(out, sql->row_count);
 	}
 }