条件选择（如果存在）

Question

除了选择字段，我想使用SQL代码来验证表[grlf_lig]是否存在，如何在notifyix上进行验证？

我使用Sheel代码进行验证，但是它很慢，因为它必须将文件记录在磁盘上并进行验证。

dbaccess sysmaster <<EOF  > /dev/null 2> /dev/null
set isolation to dirty read;
unload  to '$TMPFILE' delimiter "|"
select x0.sid,
x0.username,
x0.hostname,
x1.sqs_dbname,
dbinfo("UTC_TO_DATETIME",x0.connected) AS conn_dt
from
sysmaster:"informix".syssessions x0,
sysmaster:"informix".syssqlstat x1,
sysmaster:"informix".sysnetworkio n
where ( x0.sid = x1.sqs_sessionid ) and hostname is not NULL  and 
trim(hostname) <> ''
and trim(hostname) <> '-' AND sqs_dbname NOT LIKE 'sys%' AND sqs_dbname <> 
'-' AND n.sid = x0.sid
EOF

for I in `cat $TMPFILE`; do

 SID=`echo $I | awk -F'|' '{print $1}'`
 BD=`echo $I | awk -F'|' '{print $4}'`
 echo "" > $FILE
 dbaccess $BD <<EOF  > /dev/null 2> /dev/null
 set isolation to dirty read;
 unload to "$FILE" delimiter '|'
 select first 1 sid_f_lig, max(dtlogin_f_lig), winuser_f_lig, tty_f_lig, 
 cod_capli from grlf_lig where
 ( sid_f_lig = '$SID' and dtlogout_f_lig is null )
 group by  sid_f_lig, winuser_f_lig, tty_f_lig, cod_capli
 EOF

 if [ -s $FILE ]; then
    cat $FILE >> $FILE1
 fi
 done

我想快速获得结果，因为要花费很长时间才能获得结果。