📥 SQL LOAD DATA / BULK INSERT – High-Speed Data Import Guide

🧲 Introduction – Why Use LOAD DATA or BULK INSERT?

Manually inserting data row-by-row using INSERT statements is fine for small jobs. But when you’re dealing with large datasets, such as CSVs or flat files with millions of rows, you need high-performance options like LOAD DATA (MySQL) or BULK INSERT (SQL Server).

These commands allow you to load data in bulk directly into a SQL table—saving time, reducing load, and improving efficiency.

🎯 In this guide, you’ll learn:

• How to use LOAD DATA in MySQL
• How to use BULK INSERT in SQL Server
• Format requirements and file structure
• Best practices and performance tips

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🔄 1. LOAD DATA INFILE in MySQL

LOAD DATA INFILE '/path/to/file.csv'
INTO TABLE employees
FIELDS TERMINATED BY ',' 
ENCLOSED BY '"'
LINES TERMINATED BY '\n'
IGNORE 1 ROWS;

✅ Explanation:

• INTO TABLE employees: Target table
• FIELDS TERMINATED BY ',': CSV delimiter
• ENCLOSED BY '"': Handles quoted strings
• IGNORE 1 ROWS: Skips the header row

💡 Tip: File path must be accessible to the database server and local file permissions must allow reading.

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📦 2. BULK INSERT in SQL Server

BULK INSERT employees
FROM 'C:\data\employees.csv'
WITH (
  FIELDTERMINATOR = ',',
  ROWTERMINATOR = '\n',
  FIRSTROW = 2
);

✅ Explanation:

• BULK INSERT: Loads data into a SQL Server table
• FIRSTROW = 2: Starts from second row (skip header)
• FIELDTERMINATOR / ROWTERMINATOR: Specify delimiters

⚠️ Note: You may need to enable Ad Hoc Distributed Queries or configure BULKADMIN permissions.

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📊 3. File Format Expectations

Requirement	MySQL (LOAD DATA)	SQL Server (BULK INSERT)
File type	.csv, .txt, tab-separated	.csv, .txt, fixed or delimited
Header skip option	IGNORE n ROWS	FIRSTROW = n
Delimiter control	FIELDS TERMINATED BY	FIELDTERMINATOR
Quoted strings	ENCLOSED BY '"'	Handled with FORMATFILE or defaults

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🧪 4. Real-World Use Case – Employee Import

🗃️ CSV File Example (employees.csv)

id,name,position,salary
1,John Doe,Manager,75000
2,Jane Smith,Developer,65000

✅ SQL Server

BULK INSERT employees
FROM 'C:\import\employees.csv'
WITH (
  FIELDTERMINATOR = ',',
  ROWTERMINATOR = '\n',
  FIRSTROW = 2
);

✅ MySQL

LOAD DATA INFILE '/import/employees.csv'
INTO TABLE employees
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
IGNORE 1 ROWS;

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⚙️ 5. Performance Tips for Bulk Loading

💡 Best Practice	⚠️ Avoid This
Disable indexes before loading	Loading into indexed tables (slow)
Use IGNORE or REPLACE options (MySQL)	Allowing duplicate key errors
Use batch commits or minimal logging	Logging every row change (SQL Server)
Clean and validate CSV format before load	Loading malformed data files
Use staging tables for validation	Writing directly to production tables

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🛡️ 6. Security Considerations

• MySQL may disable LOAD DATA LOCAL by default for security reasons.
• SQL Server may restrict bulk inserts without proper permissions (BULKADMIN role).
• File paths must be accessible to the database service (local or remote execution may vary).

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🧠 7. LOAD vs INSERT – Performance Comparison

Method	Speed	Use Case
INSERT INTO	Slow	Small sets, manual inserts
LOAD DATA INFILE	Very Fast 🚀	Large CSV/file-based imports
BULK INSERT	Very Fast 🚀	SQL Server-specific bulk loading

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📌 Summary – Recap & Next Steps

Using LOAD DATA and BULK INSERT dramatically improves performance when importing large datasets. These tools are essential for ETL pipelines, initial data loads, and batch data migration.

🔍 Key Takeaways:

• LOAD DATA (MySQL) and BULK INSERT (SQL Server) are optimized for importing files.
• Specify field and row delimiters carefully.
• Always validate data files and permissions before loading.

⚙️ Real-World Relevance:
Used in data warehousing, reporting systems, and legacy migrations to move data at scale without heavy scripting.

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❓ FAQ – SQL LOAD DATA / BULK INSERT

❓ Can I skip the header row in CSV during import?

✅ Yes:

• MySQL: IGNORE 1 ROWS
• SQL Server: FIRSTROW = 2

❓ What permissions do I need for BULK INSERT?

✅ You must be in the BULKADMIN role or have appropriate file access permissions in SQL Server.

❓ What’s the difference between LOAD DATA and INSERT INTO ... SELECT?

✅ LOAD DATA reads from files, while INSERT INTO ... SELECT copies between tables.

❓ Does LOAD DATA INFILE work remotely?

✅ Only if LOCAL is enabled (LOAD DATA LOCAL INFILE), and client/server both support it.

❓ How can I prevent duplicate rows?

✅ Use:

• IGNORE to skip duplicates
• REPLACE to overwrite duplicates (MySQL)

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