Solution.java

class SQL {
    private Map<String, List<List<String>>> tables;

    public SQL(List<String> names, List<Integer> columns) {
        tables = new HashMap<>(names.size());
    }

    public void insertRow(String name, List<String> row) {
        tables.computeIfAbsent(name, k -> new ArrayList<>()).add(row);
    }

    public void deleteRow(String name, int rowId) {
    }

    public String selectCell(String name, int rowId, int columnId) {
        return tables.get(name).get(rowId - 1).get(columnId - 1);
    }
}

/**
 * Your SQL object will be instantiated and called as such:
 * SQL obj = new SQL(names, columns);
 * obj.insertRow(name,row);
 * obj.deleteRow(name,rowId);
 * String param_3 = obj.selectCell(name,rowId,columnId);
 */