Build a SQL Query BuilderStep 2 of 5

Where Conditions

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Step 2 - Where Conditions

Real queries filter rows. A WHERE clause is a list of conditions joined by AND. Because a query can have many conditions, the builder collects them one call at a time.

Implement where(condition). Append the condition string to self.wheres and return self so the call keeps chaining.

The build method has already been extended: when self.wheres is non-empty it appends a space, the word WHERE, and the conditions joined by the four-character separator space-AND-space. With no conditions the clause is omitted entirely.

Hints
Starter code
class QueryBuilder:
    def __init__(self):
        self.columns = []
        self.table = None
        self.wheres = []
        self.order = None
        self._limit = None

    def select(self, *cols):
        self.columns = list(cols)
        return self

    def from_(self, table):
        self.table = table
        return self

    def where(self, condition):
        """Append condition to self.wheres and return self."""
        # TODO: record this condition at the end of self.wheres so the clauses
        #   keep the order they were added in, then hand back the builder itself
        #   so the caller can keep chaining onto it.
        pass

    def build(self):
        cols = ", ".join(self.columns) if self.columns else "*"
        sql = "SELECT " + cols + " FROM " + self.table
        if self.wheres:
            sql += " WHERE " + " AND ".join(self.wheres)
        return sql
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