LOCK for ISAM
Added May 2024
LOCK #ch
Applicable only when LOKSER enabled, LOCK is used to lock the primary index (ch) after locating a record using a secondary index. This is automatic when the record is located via the primary index.
Example
The following illustrates looking up a record in the secondary index and then deleting it. The LOCK statement is used to first lock the primary index before the delete operation.
OPEN #PCH, "WIDGET", ISAM'INDEXED, RECSIZ, RECNO ! primary index & data
OPEN #SCH, "WIDGET2", ISAM'INDEXED, RECSIZ, RECNO ! secondary index
...
ISAM #SCH , 1, KEY ! lookup key in secondary index SCH
IF ERF(SCH) = 33 then
? "Record not found"
ELSEIF ERF(SCH) # 0 then
GOTO ISAM'ERROR
ELSE
LOCK #PCH ! lock primary index
READL #PCH, REC
ISAM #SCH, 4, SKEY ! delete secondary key
IF ERF(SCH) # 0 GOTO ISAM'ERROR
ISAM #PCH, 4, PKEY ! delete primary key
IF ERF(PCH) # 0 GOTO ISAM'ERROR
ISAM #PCH, 6, PKEY ! delete data rec
IF ERF(PCH) # 0 GOTO ISAM'ERROR
WRITE #PCH, REC
ENDIF
See Also
