CS50, LECTURE 7: SQL QUESTIONS FULLY SOLVED & UPDATED 2024

schema decide on the _________, or format, of our data in advance by choosing the columns database a file or program that stores data flat-file database a database that only contains one table of data; example: CSV files KeyError error raised when a dictionary key is not found canonicalize standardizing data (e.g. all uppercase, strip whitespace before and after) relational databases programs that store data, ultimately in files; similar in spirit to spreadsheets, but instead are implemented in software and give us more features, use more data structures, so that we can search and store data more efficiently (vs a flat file, e.g. CSV) SQL a special-purpose programming language for accessing and manipulating data stored in a relational database four basic operations supported by any relational database CRUD: Create: add new data Read: access and load into memory new data Update: manipulate Delete: remove SQL CRUD commands CREATE, INSERT SELECT (Read) UPDATE DELETE table objects that store the data in the relational database (similar to spreadsheets) B-tree a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time index tell database programs to create additional data structures so we can search and sort with logarithmic time; a lookup table that is small, fast, and optimized for quickly finding records users need to search frequently. SQL injection attack occurs when users enter a SQL statement into a form in which they are supposed to enter a name or other data Race Condition results when several threads try to access and modify the same data concurrently SQL transaction locks rows in a database, such that a particular set of actions are guaranteed to happen together; addresses race conditions