what is difference between lookup and merge join in ssis?
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A Merge Join is designed to produce results similar to how JOINs work in SQL. The Lookup component does not work like a SQL JOIN. ... With a Merge Join you will get the desired output. With a Lookup, where input 2 is the look up source, the output will be one row per invoice, no matter how many rows exist in input 2.
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UNION vs. The join such as INNER JOIN or LEFT JOIN combines columns from two tables while the UNION combines rows from two queries. In other words, join appends the result sets horizontally while union appends result set vertically.
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2. The Joiner Transformation supports Normal,Right Outer, Left Outer, and Full Outer JOINs. You cannot combine records based on a join condition in Union Transformation. The Union Transformation is equivalent to a UNION ALL statement in SQL, which combines data vertically from multiple sources.
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(INNER) JOIN: Returns records that have matching values in both tables. LEFT (OUTER) JOIN: Return all records from the left table, and the matched records from the right table. RIGHT (OUTER) JOIN: Return all records from the right table, and the matched records from the left table.
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Lookup is basically a specific dataset which is keyed. This can be used to mapping values as per the data present in a particular file (serial/multi file). ... Sometimes, hash-joins can be replaced by using reformat and lookup if one of the input to the join contains less number of records with slim record length.
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Usually, when asked about what's the main difference between nested loop joins and hash joins, the answer will be that hash join uses a hash-table based lookup mechanism while nested loop doesn't or that the hash join can use cursor work-area memory (allocated in UGA) for buffering rows, while nested loops join can not ...
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Difference between JOIN and INNER JOIN JOIN returns all rows from tables where the key record of one table is equal to the key records of another table. The INNER JOIN selects all rows from both participating tables as long as there is a match between the columns.
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Lookup transformations perform lookups by joining data in input columns with columns in a reference dataset. ... In contrast, the Fuzzy Lookup transformation uses fuzzy matching to return one or more close matches in the reference table. Fuzzy lookups are commonly used to standardize addresses and names.
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Both joins and unions can be used to combine data from one or more tables into a single results. They both go about this is different ways. Whereas a join is used to combine columns from different tables, the union is used to combine rows.
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INNER JOIN: returns rows when there is a match in both tables. LEFT JOIN: returns all rows from the left table, even if there are no matches in the right table. RIGHT JOIN: returns all rows from the right table, even if there are no matches in the left table. ... Note :It will return all selected values from both tables.
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What's the difference between a lookup type and a value set? A "lookup type" consists of lookups that are static values in a list of values. ... A table-validated "value set" may consist of values that are validated through a SQL statement, which allows the list of values to be dynamic.
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Inner Join vs. Outer Join. In SQL, a join is used to compare and combine — literally join — and return specific rows of data from two or more tables in a database. An inner join finds and returns matching data from tables, while an outer join finds and returns matching data and some dissimilar data from tables.
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The first and most obvious difference is that Merge can only accept two datasets while Union All can accept more than two datasets for input. The second difference is that Merge requires both datasets to be sorted while Union All does not require sorted datasets.
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There are different types of joins available in SQL: INNER JOIN: returns rows when there is a match in both tables. LEFT JOIN: returns all rows from the left table, even if there are no matches in the right table. RIGHT JOIN: returns all rows from the right table, even if there are no matches in the left table.
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If you imagine this visually: With a full outer join you add columns and widen your result rows (tuples) with columns (attributes) from the rows (tuples) of the source tables. If you union, you only add rows (tuples) of the same structure.
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In simple terms, joins combine data into new columns. If two tables are joined together, then the data from the first table is shown in one set of column alongside the second table's column in the same row. Unions combine data into new rows.
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Joining is where you are able to combine data from the SAME data source, for example worksheets in an Excel file or tables in an Oracle database. ... Blending is where you able to combine data from DIFFERENT data sources, for example a worksheet in Excel with a table from an Oracle database.