delete column moved to low level table operation file

Ignore-this: d95aac67b1bc99c233bf8cada024b42c

darcs-hash:20110416004050-067c0-5f30fb39f0d5eacd59db2befd7e45b83459ca451.gz

1 files changed, 42 insertions, 1 deletions

diff --git a/libBasicTableOperations.tcl b/libBasicTableOperations.tcl
index 4eca8c8..68781dc 100755
--- a/libBasicTableOperations.tcl
+++ b/libBasicTableOperations.tcl
@@ -1,6 +1,6 @@
 #!/bin/sh
 # FILE: "/home/evmik/src/my_src/GradeBook/libBasicTableOperations.tcl"
-# LAST MODIFICATION: "Fri, 15 Apr 2011 20:01:22 -0400 (evmik)"
+# LAST MODIFICATION: "Fri, 15 Apr 2011 20:38:36 -0400 (evmik)"
 # (C) 2011 by Eugeniy Mikhailov, <evgmik@gmail.com>
 # $Id:$
 # vim:set ft=tcl: \
@@ -26,6 +26,18 @@ proc getColListFromTable {table} {
 	return $all_column_names	
 }
 
+proc colList2sqlColStr { col_list } {
+	set sqlStr {}
+	foreach col $col_list {
+		if {$sqlStr ne ""} {
+			set sqlStr $sqlStr,\"$col\"
+		} else {
+			set sqlStr \"$col\"
+		}
+	} 
+	return $sqlStr
+}
+	
 proc SelectColvalueFromTable { table  column_of_interest col row_value } {
 	# select value of 'column_of_interest' from 'table' where 'col'='row_value'
 	set value {}
@@ -72,3 +84,32 @@ proc doesColumnExists {col  table} {
 	}
 }
 
+proc DeleteColumnFromTable { table columnname } {
+	if { $columnname eq "" } {
+		htmlErrorMsg  "empty column names are not permitted"
+	}
+
+	if { [doesColumnExists $columnname $table] } {
+		# removing the column name to be deleted from total list
+
+		set old_column_list [getColListFromTable $table]
+		set new_column_list [removeElementFromList $columnname $old_column_list]
+		set sql_new_column_str [colList2sqlColStr $new_column_list]
+		set eval_str "BEGIN TRANSACTION;
+			CREATE TEMPORARY TABLE \'${table}_backup\'($sql_new_column_str);
+			INSERT INTO \'${table}_backup\' SELECT $sql_new_column_str FROM \'${table}\';
+			DROP TABLE \'${table}\';
+			CREATE TABLE \'${table}\'($sql_new_column_str);
+			INSERT INTO \'${table}\' SELECT $sql_new_column_str FROM \'${table}_backup\';
+			DROP TABLE \'${table}_backup\';
+			COMMIT;"
+		set err [catch {db eval $eval_str  } errStat]
+		if { $err } {
+			htmlErrorMsg  $errStat 
+			dbg  "the following error happen: $errStat" 3
+		} 
+	} else {
+		htmlErrorMsg  "No column $columnname in the table $table"
+	}
+}
+