select count(*) from Business where .....; count(*)效率较低,强烈建议count(逐渐字段)的形式来优化sql,如count(Bussiness_id)!
String sql= "SELECT Count(*) FROM T_BUSINESSHISTORY where " + " ONTIME between TO_DATE('2012-04-1 08:00:00','yyyy-mm-dd hh24-mi-ss') " + " and TO_DATE('2012-04-01 9:00:00','yyyy-mm-dd hh24-mi-ss') and ONLON/3600000 between "+l_u_lon+" and "+l_u_lon2+" and ONLAT/3600000 between "+l_u_lat2+" and "+l_u_lat;
String sql= "SELECT Count(*) FROM T_BUSINESSHISTORY where " + " ONTIME between TO_DATE('2012-04-1 08:00:00','yyyy-mm-dd hh24-mi-ss') " + " and TO_DATE('2012-04-01 9:00:00','yyyy-mm-dd hh24-mi-ss') and ONLON/3600000 between "+l_u_lon+" and "+l_u_lon2+" and ONLAT/3600000 between "+l_u_lat2+" and "+l_u_lat; “ONLON/3600000” “ONLAT/3600000”把计算改到条件里面去先计算好,“TO_DATE('2012-04-1 08:00:00','yyyy-mm-dd hh24-mi-ss')” 不可以直接写成“2012-04-1 08:00:00”吗?
count(*)效率较低,强烈建议count(逐渐字段)的形式来优化sql,如count(Bussiness_id)!
" ONTIME between TO_DATE('2012-04-1 08:00:00','yyyy-mm-dd hh24-mi-ss') " +
" and TO_DATE('2012-04-01 9:00:00','yyyy-mm-dd hh24-mi-ss') and ONLON/3600000 between "+l_u_lon+" and "+l_u_lon2+" and ONLAT/3600000 between "+l_u_lat2+" and "+l_u_lat;
" ONTIME between TO_DATE('2012-04-1 08:00:00','yyyy-mm-dd hh24-mi-ss') " +
" and TO_DATE('2012-04-01 9:00:00','yyyy-mm-dd hh24-mi-ss') and ONLON/3600000 between "+l_u_lon+" and "+l_u_lon2+" and ONLAT/3600000 between "+l_u_lat2+" and "+l_u_lat;
“ONLON/3600000” “ONLAT/3600000”把计算改到条件里面去先计算好,“TO_DATE('2012-04-1 08:00:00','yyyy-mm-dd hh24-mi-ss')” 不可以直接写成“2012-04-1 08:00:00”吗?