Solaris

awk 'BEGIN{i=1}NR<3{print}{a[i%3]=$0;i++}END{printf("%s\n%s\n%s\n",a[(i-3)%3],a[(i-2)%3],a[(i-1)%3]);print i}' input.txt

awk '!/^SQL/&&!/^ *$/ {Ar[++i]=$0}
     /Table/,/--*/
     END{for (j=i-nrln+1;j<=i;j++) print Ar[j]}
    ' nrln=3 file
Tablespace                      Size (GB)  Free (GB)     % Free     % Used      
------------------------------ ---------- ---------- ---------- ----------      
WMHAPP_DS                            8.93       7.19         80         20      
WMHAIT_DS                              32      24.05         75         25      
WMHA_DM                               348      37.49         11         89