Update README.md

Author: frankiechapson

README.md

@@ -1,2 +1,63 @@
-# Export-and-Import-LOB-values
-Oracle PL/SQL solution to move LOB data with text files
+
+# Export and Import LOB values
+
+## Oracle PL/SQL solution to move LOB data with text files
+
+## Why?
+
+Because I did not find any useful and easy solution for exporting and importing LOB data.
+ 
+The **EXP_IMP_LOB** package can export and import **CLOB, NCLOB, BLOB** type column data using simple SQL (text) files.
+
+## How?
+
+First of all install the package onto both source and target schemas.
+To export run this select
+
+    select * from table( EXP_IMP_LOB.EXPORT('table_name','lob_column_name','condition') );
+
+where the *Table_Name* and *LOB_Column_Name* define the data column and the optional Condition defines the row or rows. 
+If there is no condition, then every row data will be exported row by row.
+    
+Example:
+
+    select * from table( EXP_IMP_LOB.EXPORT('person','image','id=103' ) );
+
+Result:
+
+    / ******************************************************
+        TABLE  :PERSON
+        COLUMN :IMAGE
+        ROW    :103
+    ****************************************************** /
+    BEGIN
+        EXP_IMP_LOB.IMPORT_NEW;
+        EXP_IMP_LOB.IMPORT_APPEND ( 'FFD8FFE000104A464....23232323232');
+        EXP_IMP_LOB.IMPORT_APPEND ( '32323232323232323....798999AA2A3');
+        .........
+        EXP_IMP_LOB.IMPORT_APPEND ( 'B2316524267279AA9....51401FFFD9');
+        EXP_IMP_LOB.IMPORT_UPDATE ( 'PERSON','IMAGE','103' ); 
+        COMMIT;
+    END;
+    /   
+ 
+So, the export converts the binary data to 400 char length hexa strings and creates a script from it.
+I used ..... to symbolize many chars, because that is only a sample above.
+DO NOT ORDER THE RESULT!
+To import, you only have to install the package onto the target schema too and run this script above in the target schema.
+That's all.
+
+...more:
+
+* The source and target *table name, column name* must be the same!
+* The Table (both source and target) must have Primary key and they must be identical.
+* The EXPORT function can detect the primary key automatically. Theoretically it can manage composed keys too...
+* The size of a hexa string is defined in G_LENGTH global variable. 200 chars means 400 hexa chars.
+* The additional procedures:
+* **IMPORT_NEW**: resets the package variables to prepare it to accept a new LOB
+* **IMPORT_APPEND** : converts the hexa string to a binary data and append it the package variable
+* **IMPORT_UPDATE** : updates the given table, row, column with the package variable
+* **DIRECT_SQL** : executes the given SQL using the global LOB variable as a parameter. eg:     
+
+    EXP_IMP_LOB.DIRECT_SQL( 'insert into ANY_TABLE ( ID, IMAGE ) values ( 123, :1 )' ); 
+