How should I practice Execute In-Memory SQL Storage Operations?

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Execute In-Memory SQL Storage Operations

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Problem statement

Execute a finite ordered batch against an in-memory database service. The five input arrays have equal length. Return one result per operation.

CREATE_DB creates a database.
CREATE_TABLE creates a table in an existing database.
INSERT stores values[i] at a new integer row ID.
READ returns the current value for an existing row.
UPDATE replaces the value of an existing row.
DELETE removes an existing row.

A successful write returns OK. A missing parent, missing row, or duplicate create/insert returns ERROR and changes no state. Fields unused by an operation may contain the empty value for their type.

Function

executeStorageOperations(operations: String[], databases: String[], tables: String[], ids: int[], values: String[]) → String[]

Examples

Example 1

operations = ["CREATE_DB","CREATE_TABLE","INSERT","READ","UPDATE","READ","DELETE","READ"]databases = ["sales","sales","sales","sales","sales","sales","sales","sales"]tables = ["","orders","orders","orders","orders","orders","orders","orders"]ids = [0,0,7,7,7,7,7,7]values = ["","","new","","paid","","",""]return = ["OK","OK","OK","new","OK","paid","OK","ERROR"]

The update changes the stored row and deletion removes it.

Example 2

operations = ["CREATE_TABLE","CREATE_DB","CREATE_DB","CREATE_TABLE","INSERT","INSERT"]databases = ["x","x","x","x","x","x"]tables = ["t","","","t","t","t"]ids = [0,0,0,0,1,1]values = ["","","","","a","b"]return = ["ERROR","OK","ERROR","OK","OK","ERROR"]

Parents must exist and duplicate creates or inserts fail.

Example 3

operations = []databases = []tables = []ids = []values = []return = []

An empty batch has no results.

Constraints

0 <= operations.length <= 100000 and all five arrays have that length.
Every operation is one of the six documented uppercase strings.
Database and table names used by their operations are nonempty and at most 100 characters.
Row IDs are nonnegative, and stored values have at most 1000 characters.