One of the most important skills for data analysts to have is a good understanding of Structured Query Language, or SQL. If you want to work in this field, you should be ready for the questions that might be asked of you.
We made a list of tough SQL interview questions and gave you our answers to help you prepare for your interview. To make things easier for you, we put these questions into groups based on the level of skill needed to answer them.
BCP (Bulk Copy Program) is an essential tool for any SQL Server professional. It allows fast and efficient bulk data transfers in and out of SQL Server databases. With data volumes increasing exponentially, knowledge of BCP is a must-have skillset for DBAs, developers and data engineers alike.
In this article, we will explore the top 25 BCP interview questions and answers to help you prepare for your next technical interview. Whether you’re a BCP novice or a seasoned expert, going through these questions will polish your concepts and boost confidence. Let’s get started!
1. What is BCP and what are its key features?
BCP or Bulk Copy Program is a command-line utility built into SQL Server to import and export large volumes of data quickly Some key features of BCP are
- High-speed data transfer from/to flat files
- Minimal logging for faster performance
- Support for various formats like CSV, native, XML etc.
- Can handle large data sizes ranging into millions of rows
- Ability to export data from tables and views
- Customizable field and row terminators
In a nutshell, BCP is optimized for performance and can move huge amounts of data between SQL Server and files blazingly fast
2. When should you use BCP over other SQL Server data transfer options?
BCP outperforms other methods like BULK INSERT or INSERT statements when you need to move large datasets between SQL Server and files. Specifically, BCP is the best fit when:
- Migrating data from one SQL Server to another
- Populating data warehouses
- Backing up and restoring very large databases
- Transferring data over slow networks
- Loading data from daily extracts or dumps
BCP is designed to handle millions of rows efficiently. For smaller data volumes, BULK INSERT or SSIS may be preferable.
3. Explain the syntax for import and export using BCP
The syntax for BCP import is:
bcp database_name.schema.table_name IN datafile -f formatfile.fmt -T -S server_name For export:
bcp database_name.schema.table_name OUT datafile -f formatfile.fmt -T -S server_nameWhere:
- IN/OUT specifies import or export direction
- datafile is the path to the data file
- -f refers to the format file
- -T uses a trusted connection
- -S provides the server name
4. How does BCP handle data types?
BCP stores data in either native or character format during transfer.
For native format, data types like int, decimal etc. are represented in their binary format. This makes transfers faster.
Character mode converts all data into character strings for portability across platforms. Numerical data is converted to ASCII representations.
By default, BCP uses the native format for bulk operations. The -n switch explicitly specifies native handling while -c indicates character.
5. How can you specify field and row terminators in BCP?
BCP allows specifying field and row terminators used in the data files via the -t and -r parameters respectively.
For example:
-t , //fields separated by comma-r n //rows delimited by newlineCommon field terminators are comma, tab, pipe etc. Row terminators can be newline or carriage return.
If terminators are not provided, BCP uses tab for field and newline for row by default.
6. What is the role of format files in BCP?
Format files in BCP are used to define the layout of the data file in terms of columns, datatypes, widths, terminators etc. They act as a schema that BCP follows while interpreting the data file during bulk import.
The syntax of format files is similar to create table statements. Some key sections are:
- Data columns with width and storage type
- Field and row terminators
- Format options like quoted/unquoted identifiers etc.
Format files provide flexibility while transferring data between different formats.
7. How can you ensure data integrity during BCP import?
To ensure data integrity when importing using BCP:
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Use format files to guarantee correct data type mapping from files.
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Specify batch size e.g. -b 10000, to commit rows in batches. If errors arise, only a batch is affected.
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Utilize identity inserts to avoid duplication of identity columns.
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Set max errors allowed with -m before BCP terminates due to errors.
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Hold off creating indexes on the destination table until after import to improve speed.
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Validate incoming data before inserting into production tables.
8. What is the difference between BCP and Bulk Insert?
While both BCP and Bulk Insert quickly load data into SQL Server, there are some key differences:
- BCP is a command line utility while Bulk Insert is a T-SQL command
- BCP supports native and XML formats, Bulk Insert only supports flat files
- BCP can export data out of SQL Server, Bulk Insert can only import data in
- BCP works across databases, Bulk Insert loads data only into SQL Server
- Bulk Insert performs better for smaller local data loads
9. How does BCP resume if a failure occurs midway?
If an error occurs midway during a BCP import or export operation, BCP aborts the process. To resume from failure:
- For export, re-run the BCP OUT command appending
-F firstrow -L lastrowto specify range - For import, use
-F firstrowto skip rows until the failed batch, then re-run BCP IN - Alternatively, split the data into multiple files and transfer file-by-file
This avoids re-processing already transferred data.
10. How can you use BCP to migrate data between servers?
Follow these steps to migrate data between SQL Server instances using BCP:
- Export data from source server into a file using BCP OUT
- Copy the data file to the destination server
- Import data into target database using BCP IN
- Repeat for all necessary tables
Additional steps like recreating clustered indexes post-import may be required for completeness.
11. What are some real-world use cases where BCP is preferred?
Some real-world use cases where BCP outperforms other methods are:
Data warehousing – Loading data from transactional systems into data warehouses
ETL – Populating staging tables from daily extract files
Archiving – Moving old data from production tables to archive files
Backup & Restore – Faster backup of large databases into files
**Migration
SQL interview questions for experienced specialists
If you are a professional with a strong technical background, here is a list of tough SQL interview questions.
1. What is SQL injection?
Unfortunately, SQL injection is a type of code injection that lets bad code get to private information that shouldn’t be shown.
2. What is a trigger in SQL?
A “trigger” is a type of procedure that runs automatically when something in the database goes off. One example is a Data Manipulation Language event that sets off a DML trigger when a user tries to change some data.
3. Can we disable a trigger?
Yes, it’s possible to disable a trigger. For this purpose, use “DISABLE TRIGGER triggerName ON<>. If you need to disable all the triggers, use DISABLE TRIGGER ALL ON ALL SERVER.
4. How to use LIKE in SQL?
When we need to find a certain pattern in a column, we use the LIKE operator in the WHERE clause. For example:
5. How is a non-clustered index different from a clustered index?
A clustered index determines the order in which the data are stored in a table. A non-clustered index, in turn, does not sort the data inside the table. Actually, non-clustered index and table data are stored in two separate places.
6. What is ISAM?
IBM came up with ISAM, which is also called the Indexed Sequential Access Method, as a way to store and get data from secondary storage systems.
7. What is Database Black Box Testing?
BlackBox testing implies testing interfaces and database integration. It includes data mapping, checking the data that comes in, and checking the data that goes out from query functions.
8. What is the COMMIT in SQL?
We use the COMMIT statement to end a transaction and guarantee that all changes will stay in place. A transaction, on the other hand, is a set of SQL statements that the Oracle Database sees as a single unit.
9. What is the difference between TRUNCATE and DROP statements?
TRUNCATE statement removes all rows from the table while the DROP command deletes a table from a database. In both cases, the operation cannot be rolled back.
10. What is a collation?
There are rules that tell the database engine how to sort and compare the character data. These rules are called collation.
SQL interview questions for freshers
Rookies can expect to be asked the following basic SQL interview questions:
1. What is Database?
The term database describes an organized collection of logically related information stored, accessed, modified, and updated electronically.
2. What is a database management system?
A database management system, or DBMS, is a piece of software that lets you store, retrieve, and control data in a database.
3. What is a Relational database management system? What is the difference between an RDBMS and DBMS?
A relational database management system is a piece of software that stores information in tables so that it can be used with other sets of information. Several users can access RDBMSs. At the same time, in DBMSs, data are stored in files that one user can only manage.
SQL 2012 Bulk Copy Program (BCP)
FAQ
Which BCP tool is used to copy a bulk of data?
What is the difference between BCP and bulk insert?
What are BCP commands?
What is the batch size of BCP import?
What is Bulk Copy Program aka BCP?
The Bulk copy program aka bcp is the console application used to export and import data from text files to SQL Server or vice versa. It is very popular because it is fast and easy to download. This tool is installed by default with SQL Server. It is usually installed in the following path:
What does BCP do in SQL Server?
The bcp utility (Bcp.exe) is a command-line tool that uses the Bulk Copy Program (BCP) API. The bcp utility performs the following tasks: Bulk exports data from a SQL Server table into a data file. Bulk exports data from a query. Bulk imports data from a data file into a SQL Server table. Generates format files.
What does BCP do when bulk copying data?
The bcp utility allows you to refer to a format file when bulk copying data, saving you from reentering format information interactively. To use a format file, you need to specify the -f option. Creating an XML format file requires the additional -x option. For more information, see Create a Format File (SQL Server). You must specify nul as the value (format nul).
How can I use BCP on Linux?
To use bcp on Linux, you need to install the SQL Server command-line tools sqlcmd and bcp. For detailed information about using bcp with Azure Synapse Analytics, see Load data with bcp. The bcp utility can be used to import large numbers of new rows into SQL Server tables or to export data out of tables into data files.
