See all Options detailed in the navigation pane on the left

SQL : Use the Send EMPTY STRING instead of default NULL if you need to have a column with EMPTY values transferred as an empty string
CAREFUL : if you use this option then you will not be able to query the Table using [select * from TableName where ColumnName <> ''] as this will return ALL the records
The only way to use these select queries is to have a NULL value in the column and use [select * from TableName where ColumnName <> 'NULL']
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