What should be considered when retrieving values from a SQL array?

When using SQL arrays to retrieve values, it is important to keep in mind the following points:

1. Index value: The index value of SQL arrays usually starts from 1 instead of 0, so be cautious of the index range when accessing values.
2. When accessing values in an array, it is important to consider how to handle NULL values, which may be returned if a specific position in the array does not have a value.
3. Array boundary: Ensure that when accessing values, do not go beyond the boundaries, which means making sure the index being accessed is within the range of the array.
4. Data type: Make sure that the retrieved value matches the data type of the array elements, otherwise there may be type conversion errors.
5. Performance: When handling large arrays, it is important to be conscious of efficiency concerns. Avoid looping through arrays to retrieve values whenever possible, and instead consider using built-in SQL functions to improve efficiency.

In conclusion, when using SQL arrays to retrieve values, it is important to handle boundary cases and data types carefully to ensure the correctness and performance of the program.